Houserules: Damage (Hardened, Toxins, Grenades)

SR6 restructured damage codes and soak pools. This heavily decreases one-shot chances, so that’s something I personally consider an advantage. This also would be why in errata they nerfed Unarmed Damage as well.

However, there’s a few things the rebalance seems to have partially missed:

  1. Grenades are 16P at ground zero, 10P~12P at 3m range
  2. Toxins, including Narcoject, go up to Power 15
  3. While Spirits have less Hardened Armor, the autosoak is still the same

Let’s start with Grenades. If you’re hit with a gun, you tend to face 4P~8P pre-soak, due to firing modes, ammo and net hits. It takes a really heavy attack to reach 10P or higher. Yet being within 3m range of an exploding grenade already does 10P, and this is to an entire group. Even a Fireball tends to not reach those damage numbers, and that faces Spell Defense zones instead of ‘1x per round, as alternative to Movement’ as defense action.

Now granted, throwing out grenades is a good way to get everyone REALLY mad at you, but they’re still far too easy and powerful an option. All it takes is one nutjob to take out a grenade, and suddenly wipes start happening. As such, reducing the damage:

  • Grenade damage is reduced
    1. HE and Frag Grenades are halved, Stun Grenades receive -2 per level (8S/6S/4S, aka same as Frag Grenades but Stun instead of Physical damage)
    2. All grenades do 75% of their current damage (rounded up).

With the first option, being hit directly will do about the same damage as a good hit, enemies nearby still take a chunk. The second keeps grenades as significantly dangerous, while decreasing the damage numbers to a point where they’re not the only valid option in dangerous fights.


Toxins are faced by Body+Willpower, so it’s easier to resist them. But one problem with Toxins is that a single point of Power left already deals the nasty side-effects. And against Injection and Ingestion, there’s limited protection possible. So unless you’re a smart street sam with a high-rating Toxin Extractor, toxins are a good way to drop you. Even a high-buffed character will perhaps score 5 hits vs a Power of 15…

On the other hand, a Gas grenade won’t immediately hit you and won’t keep hitting you, so you will not take repeated hits from them. And with Gas grenades, only within 5m do you face the maximized Power.

  • Ingestion/Injection toxins have their Power reduced to 50%
  • Contact/Inhalation toxins have their Power reduced to 75%

This way, damage numbers from toxins are more comparable to normal attacks taken. Contact/Inhalation toxins still are real dangerous within the 5m range*, however: Not only can you still get into cover and only take a single hit during the entire duration, and Toxin Resistance pools are greater than Damage Resistance pools, but Chemical Protection, Inhalators and Gas Masks also are viable counter-measures against these two vectors.

* Note that Gas Grenade rules are a bit vague, but a rule example notes 5m as the size of each range category for them.


Not everyone always manages to follow this, but here we go: A Spirit who Materializes with Materialization, receives Immunity to Normal Weapons (ItNW). This isn’t actual immunity: Immunity simply gives Hardened Armor equal to a creature’s Essence, which for Spirits equals their Force. And Hardened Armor gives an Armor Boost and autohits equal to its rating.

In other words, Materialization means a Spirit gets both their Force in Armor, and their Force in autohits on damage resistance. But only against non-magical attacks.

And unfortunately, Hardened Armor is more powerful in SR6 than in SR5. This is where the damage nerfing missed its mark.

Let’s start with numbers: In SR5, a Spirit received 2xForce as Hardened Armor, and their modified Hardened Armor gave autohits per 2. So facing 0 AP, they had Force autosoak. In SR6, they receive Force as Hardened Armor, which equals their autohits. So while they no longer add Armor to their Soak pool, their autohits remained the same, meaning the overall reduction in attack DV means they actually take less damage than before.

Worse, this is no longer reduced by AP. So in the past, the autohits could be reduced. Now, that no longer is the case. As a result, even against tough enemies with assault rifles, a Spirit will take far less damage, often none at all.

There’s three variants to discuss for nerfing this, of which two are shamelessly stolen from people on Facebook, at Shadowrun 6th Edition Chummers. Fortunately we don’t have to nerf too much, because currently there’s only 2 critters with Hardened Armor: Spirits, and Sharks. (Shame that that’s going to get errataed eventually. XD)

  1. Hardened Armor only gives Rating/2 Autohits on soak
  2. ItNW gives rating 3 Hardened Armor
  3. ItNW gives rating 4 Hardened Armor against ranged attacks, and rating 2 against melee attacks

The first variant scales with Force, so high-Powered spirits are still much tougher to injure. With the second, both weak and strong spirits take about the same damage, so even weak Spirits are still a threat.

The third variant follows the second variant, but buffs melee against Spirits. This nerf where Spirits their protective measures don’t work well up close and personal, is semi-representative of the old classic Attack of Will. Now watch a Troll headbutt that big mean Spirit in front of them. Just hope they don’t have Energy Aura.

Houserules: Movement Power

The Movement power is what allows some spirits to move at incredible speed, as well as either buff or restrain others by either multiplying or dividing it with the Spirit’s Magic (which equals Force).

In SR4 this power had only two restrictions listed: Inside terrain it controlled, and based on Body (B>M = halved effect, B>2*M = no effect). SR5 has more detail to it, going back to SR3’s description and talking more explicitly about terrain/domain the Spirit controls, as well as containing a separate rule for vehicles.

This unfortunately runs into two complications. First of all, what IS terrain a spirit controls? Clearly it’s not just ‘their natural habitat’, since otherwise an Air Spirit could easily target any plane they see, while a Plant spirit would rule surpreme in the jungle. Don’t even get me started on what kind of terrain would be a Guardian spirit’s natural habitat…

The second is that the power’s description went back to its SR3 version. Unfortunately, some mechanics have changed since SR3… Some even midway SR5’s development, such as Vehicles… Rather than having a significant Acceleration and Speed directly translating to m/CT, Acceleration is now a tricky number solely for Vehicle Chases (which a previous houserule already covered) and Speed simply is a limit as well as translating to how fast you can go.

I mean nobody woudl believe it’s intended that a good test on a good car could easily make it go 2^18 as fast. That’s 50 million km/hour… If we look at SR3’s Speed system the original intent seems more clear: Say you got a vehicle with an Acceleration of 10, and Speed actually is your actual speed rather than a single-digit number, then those 6 hits would translate to making the vehicle go 100 m/CT faster/slower instead, which likely (especially with deceleration rules) could actually cause it to crash due to the sudden changes.

I’ll be discussing three core Movement houserules here, two of which I have already applied in my own campaign. An important note: This has actually impacted my campaign’s balance and I’ve been thinking of ways to nerf it down for a while, which will be included as corollaries. It wasn’t that bad (sorta) with one Speedster, but with four magicians all outshining the Rigger’s speed… Not to mention it kinda ruins ambushes and all that.


Ahem. Before we go into the houserules, there’s something VERY important you should know first, a small detail of the rules that many probably missed.

Your actions and movement are declared at the START of your Action Phase. That is, you FIRST declare what all you’ll do, THEN you start executing it. (Page 158, 159, 163.) You can stop or change direction, but you cannot increase your movement after finding out some of the results of your actions. Logically the same would apply to your offensive actions, even if not explicitly stated.

So say you decide to run around a corner. If there’s an enemy waiting around it, you can’t go ‘oh then I’ll just run past him’. You can break or dive back, but not go further than originally declared. You also cannot attack him if you didn’t keep the option in mind. That’s why I make my fast players declare what their intent will be in somewhat-vague terms, for example ‘cut the first enemy that dares to get in my way in two’. That way the runner still can go around a corner and attack, assuming there is in fact an enemy within reach.

This might seem like nitpicking but when it comes to combatants easily moving 100 meters in a single Combat Turn, it becomes VERY important. You can’t walk 20m, see what enemies are where and THEN make a detailed plan for the rest of your Action Phase: Decide at the start and run into danger! You can run up a staircase but only if you knew it was there and declared the intent.

A sidenote: This also means that you got to keep a few possible outcomes in mind as player. As GM I wouldn’t give you a lot of hassle if you used an If-statement in your Action Declarations, but you got to keep in mind the highest declared movement will count for your movement allotment of the Combat Turn. Just make sure you make clear to your players what the limitations will be before they run into nasty complications, as part of the social contract.


Rule: Spirits can only use Movement on others inside Aspected Areas

There are basically three ways for an area to get Aspected in the advantage of a Tradition: The Personal Domains of some Free Spirits, frequent use by that tradition and magical lodges, in order from large to small (multiple acres, ?, very-small-region). Which means that for nearly every situation the Spirit will not be able to use Movement on others, only on themselves, fitting with the ‘only in terrain they control’ restriction being an actual restriction.

If they have the home advantage though, from defending their magician’s turf or their own… Ohboy… And that’s exactly what this houserule is about: Making it about the home-advantage. You get the enemy to fight in an area aspected in your favor, they’ll be in massive trouble against your Spirits unless they cleanse the area… Only being able to run 6 meters per Combat Turn as a 9-Agility character can REALLY hurt in combat, especially once AoE effects are put into play!


Rule: Movement against vebicles uses (M+W)d6*Accel*10/Body

Leaving aside the whole ‘Speed-changes’, which obviously no longer is intended like that with the new Speed mechanic, there’s another problem I personally have with Movement against Vehicles. Right now they have to hit a threshold, which can be MASSIVE for high-Body vehicles (9 for a Roadmaster!), but the threshold itself is merely to decide if it works! You hit a threshold 6, you suddenly count as 6 hits instead of 0. That’s plain weird. It’d make more sense if your effect was divided by Body.

Now keeping the Acceleration is an easy call since it seems logical that the better a vehicle accelerates/decelerates, the more easily a Spirit can manage to change its speed. The biggest problem is what multiplier to use. SR5 mostly uses Acceleration 1~3, where 3 is the max that matters for a Vehicle Chase, only the occasional vehicle goes above it. So a significant multiplier seems required.

A Force 6 Spirit would average 4 hits, so on a 2-Accel Body-8 Jackrabbit we’d be at 4*2/8 = 1 as base modifier. To compare, in SR3 Accel-rates were roughly from 3 to 12 and the SR5 rule employs a Body/2 for the threshold. So let’s roughly quadruple to convert back to SR3’s concepts, double to fit with B/2 and round up to x10. Now 4 hits would translate to 40 m/CT. With the modified Speed system from my previous houserules, this could actually lead to a lot of discomfort for your enemies or even a crash test.


Rule: Channeled/Possession Spirits can use Movement

A Spirit can only use Movement on itself outside terrain/domains it controls. When a Spirit possesses someone or is channeled by a magician, they form a special kind of combination which impacts Physical attributes and their resistance to mental spells. So it makes sense to also let them use their powers (such as Elemental Aura and Movement) inside these bodies, with all the downsides in the case of Elemental Aura. (Congratulations, you’re on fire, how well-protected is your gear? You’re electrifying? Enjoy the fried commlink.)

There is a big balance risk with Movement though. Even a 3-Agility character Channeling a Force 6 Spirit will suddenly have 6 Agility and 72/144 as their Movement rates… A 5-Agility with a Force 8 would hit 9*8*4 = 288 m/CT running rate, that’s ~345 km/h. Compare that to a Rigger whose 4-Speed Drones, even under my Speed table if you don’t make them lose Speed categories (which I should consider only doing for walkers, and for any drone moving indoors), can only move 150 km/h, and you realize that indeed this houserule risks favoring Movement players too much. Of course there’s downsides (spooking cars, Metamagic or Tradition sacrifice, drawing unwanted attention, cannot mask this only Manascape it, etc.) but there’s still space for a few fixes to this.

(Incidentally, I already employ slight Accel/Decel-rules and ‘Gridguide hates you and demands you wear a tracker on the highway so you don’t spook their cars’, but there’s still space for more because it’s fun but not enough.)


Rule: Movement’s buff is divided by TerrainDifficulty

Note that this does not just matter for Channeling and Possession. Great Form Spirits with 6+ net hits on the ritual can Endow a power, meaning you can now let your Spirit pass Movement on to multiple teammembers… Anyway:

On page 201 you’ll find terrain modifiers for vehicle stunts. Now we could demand Gymnastic tests for magical-boosted movement speeds, but that’s a bit tricky for long movement and rather detracts from the game. So instead we’d nerf it differently: You want to channel a spirit and run through side-streets? The buff you get is divided by 2 for the Vehicle Terrain Modifier, so a Force 6 only triples your speed instead. Want to hit the back-alleys with a Force 8? You only double instead of eightfold due to/ 4. Rounding is of course on the final movement speed, not the multiplier.

(No, these are not insane examples. Now it might be because I employ a karma<->nuyen rule but I actually do have people working towards being able to Channel Force 10 Spirits and already using Force-9 ones…)

An important note here is that the same Vehicle table includes terrain modifiers for flying. Irrelevant for metahumans themselves, but Spirits CAN fly, even if they normally don’t. Still facing some restrictions even if they take into the air is quite nice and means drones are still quite useful: A Roto-Drone managing 200 km/h (+1 Speed Category with risks, no Speed Category reduction for being a drone) would still be able to outfly a Spirit using Movement, IF directly controlled by its Rigger or solely doing normal low-altitude flying (threshold-2 is doable for 9 dice, 15% failing odds and that simply means failing and a second attempt normally).

An alternative houserule would use percentages rather than division, and of course the vehicle table is for vehicles so the descriptions would need to be altered. What is the pedestrian equivalent of sidestreets?


Two sidenotes to make. First, Harlequinn channeling would easily go faster than the speed of sound but others would have a hard time coming close. Even if you go with ‘Increase Agility stacks with Possession’ like I do, you essentially need a Force 16 Spirit in a 5[9]->17 Agility character or a Force 14 in an 8[12]->19 to barely reach 1 mach.

Sidenote two: You need ~30 m/second, so ~90 m/CT, to be able to run on water. If we count running on water with Magic as /2 for difficulty, you’d need 180 meters/CT before division. Divide by 4 for running, and 6 for a normal Force 6 Spirit and you’d need 8 Agility which is doable.

Want to walk on water without running penalties or eventual running-exhaustion? You’d need 360, say Force 9 Spirit for 10 Agility, 4 of which from the Spirit so quite doable with a bit of magic. A Force 8 would require 11~12 Agility.

My poor Valkyries

I’ve employed a few Valkyries (Guardian Spirits of a few traditions) in my games as police NPCs and unfortunately the upcoming Movement-nerf, described in next week’s houserule, will restrict them as well. ^_^ Alas.

Of course normally they fly without worries since they can just fly within the non-essential airspace and get a free clearance through Knight Errant so no slowing down for other aircrafts, but if they go towards unfriendly skies they’ll have to fly lower and will get their movement reduced. Ahwell, guess they’ll have to live with going ~175 km/h if they decide to do a sweep into Redmond. (Yes that’s Force 9. Did you think a PR6 SWAT team would send mere Force 6 Spirits into combat?)

And yes when a bunch of Valkyries, wearing Full Body Armor and wielding Ares Alphas, go into a combat zone someone WILL be playing Wagner out loud.

Houserules: Spirits breaking free

As some of you may know, Spirits can occasionally break free from their summoner and become Free Spirits. This is, however, extremely rare because for non-Allies there’s only 1 way for it to happen: The Summoner has to go unconscious from Drain damage while summoning or binding the spirit. Then and only then can they possibly break free. If they manage to hit a threshold of 3, they start Free with 1 Edge. Extra hits become extra Edge, which matters greatly but doesn’t matter now.

(For Allies they can break free during a Ritual of Change or at any point when the master goes down from Drain or Physical damage. No such rules are defined for normal spirits, in fact there’s nothing at all stating what happens if the summoner goes k.o. or dies in combat. Does the spirit stay, poof, go free? Nothing. But let’s not go into that right now.)

The actual fluff-text notes that Bound Spirits with a Force of 6 or higher tend to become free spirits. This is the same text as in SR4. Even the mechanic itself hasn’t changed. Which is, unfortunately, why the fluff description now is a load of crap.

The breaking-free test is an Edge test with threshold 3, with a possible +2 bonus. But Spirits now have Edge equal to F/2 instead of F. So a Force 6 bound spirit now has 3 dice instead of 6… Take a look at the following table:

Dice Chance Dice Chance
3 3.7% 6 32.0%
4 11.1% 7 42.9%
5 21.0% 8 53.2%

The 32% chance now is 3.7%. With +2 the 53.2% now has become a mere 21%, hardly fitting ‘tend to become free’. And the -4 from SR4 for unbound spirits now means that even with the +2 modifier added as well, a spirit needs to be Force 9 to even have the slightest chance of breaking free.

Worse, there was a way for a spirit to get more dice in SR4, though that way made no sense back then. It let them burn edge to edge the test. A test which determined how much Edge they started with as Free Spirit, so as long as they succeeded they lost nothing. That way is gone now, so it’s way harder for them to break free yet the fluff still acts as if the odds are the same.

So to summarize, F/2 makes the test near-impossible, the -4 means unsummoned got no chance at all, even the +2 hardly compensates and the spirit can’t hurt itself for better odds, plus if they could it should actually hurt them.

Which leads me to the houserule below:


Rule: Spirits trying to break free use the following table:

Situation Modifier
Unbound Spirit Edge
Bound Spirit Force
Experienced Spirit +2
Long-bound Spirit  +years bound
Rebound Spirit +rebinding attempts
Bound Burns Force Edged test allowed

The fixed unbound penalty has been replaced with a Force-related penalty. Since the Unbound Spirit uses Edge, they cannot Edge this test (Missions FAQ). Replacing it with F/2 would allow them to Edge it, but that would give them better odds than bound spirits without a price. Hence the odds are kept low like this.

The ‘memorable or frequent encounters with metahumanity’ (Street Grimoire p203) is kept.

Spirits that have spent a LOT of time tied to humanity by binding (even if not in this plane) get a bonus for being well-connected to this world. This basically lets GMs give spirits a bonus for being kept around idly. This can combine with the Experienced Spirit.

Furthermore, any rebinding attempts (either succesful or failed, including the current) add a bonus. The longer you force it to stick around, the better the odds it breaks free if you go unconscious. 🙂 Note that this could be ruled as ‘resummoning + binding the same spirit also adds the bonus even if it’s technically not rebinding’ if the GM wants a memorable spirit to have better odds.

Lastly, the SR4 Edge-burn rule gets replaced. Instead the Spirit burns a point of FORCE. Unlike Edge this actually is relevant and permanently damages the spirit no matter whether it fails or succeeds. In return both their odds and their average Edge as Free Spirit can go up quite nicely. By burning 1 point of Force, despite being summoned (so no access to their own Edge) the Spirit is allowed to actually Edge the test as normal, so Push before/after or Second Chance.

One bonus to these changes: The limit of [Force] to the Edge [Force] (3) test actually matters… Under RAW only a bound F3 spirit actually could be limited, anything above would have at most their Force in dice even with the +2.

Houserules: Conjuring

Conjuring

When it comes to summoning, there’s a lot of things that are risky for the game balance. For most of those there’s already balancing mechanisms in place, such as with the Astral Spirit Index, but there’s a few cases that are a bit problematic.

The two cases treated here are the duration of Bound Spirit Services, and dealing with Oversummoners. The first doesn’t often come up but the second I have frequently seen debates about. Debates I participated in to get the math right. The math is skippable though.

A third houserule I designed is dealing with Free Spirits, but that’s not really a rule I suspect people have a need for. Anyway, if someone has any other problems with conjuring and want some houserule input, just contact me over at Shadowrun Universe by private message. =)


Rule: Bound Spirit Services last until dusk/dawn

Since a Bound Spirit does not expire at Sunset/Sunrise, it’s possible to make them sustain specific powers/spells indefinitely. Now this comes with consequences. However since Sustaining does not require LOS and Critter Powers normally (unless GM-called otherwise) are immune to Barriers, these consequences can be easily avoided. So it’s far too easy for a mage to have a single Spirit permanently sustain Movement and Concealment on them, and possibly even Endowment.

Another problem is that buff-spells from a Spirit of Man can also become rather permanent this way, with having to blow up or slip past Mana Barriers as only concern. While having a Spirit sustain your own spell is only its Force in Combat Turns, Innate Spell would avoid that and be indefinite.

The easiest solution to this is limiting how long services last. When a service does not explicitly state a deadline, it will now not last past dusk/dawn, preventing someone from walking around with permanent buffs for 1 service per buff. You still get all the other benefits from Bound Spirits, but cannot use them as cheap buffslaves. This way the GM won’t have to dig into the other consequences, which take time, and can simply block the sneaky trick from the get-go.


Rule: Oversummoned Spirits resist with Edge

Let’s start with an important disclaimer: Some may say this is not allowed by the rules, so the GM cheats. They are wrong. p304 says that summoned and bound Spirits cannot use their own Edge pool. However, a Spirit you are Summoning is not yet summoned until you succeed, so is allowed to use Edge against the Summoning attempt itself.

There will be a time where a player decides to go down the line and use all they got to summon a Force 12 Spirit. They may score only 1 or 2 services, but the Spirit will be completely invincible. At Hardened Armor 24 they are practically immune to every kind of non-magical attack, against Indirect Spells they have a massive defense pool, against Area effects they got plenty of Initiative to burn, and they laugh in the face of any spell they resist with their Attributes. Even Direct spells are harmless, especially if it’s a Spirit with Magical Guard.

In other words, such Spirits are a game-changer. Just like how gangers stand no chance against a Force 6, even a huge PR6 enemy team will be butchered by a Force 12. If used for the climactic boss-fight where everything is on the line, such a high-risk move makes sense. The problem arises when it is NOT a high-risk move and used as a frequent weapon instead.

Just like how wards are limited in how much they balance out Quickening, so is drain in itself limited in how they balance out Summoning. Now a anti-Summoning dice pool of 12, with hits doubled in drain, may seem like it is a decent risk. But at the same time it’s the same dicepool that is used against Binding, and people still have Force 6 Spirits. Sure, they got a safer environment but it still boils down to the same success chances and drain risks.

WARNING: The next section contains a lot of math. Skip to “Math Done” to get to the abbreviated version.

Let’s take a look at a slightly-buffed Shaman. At 5 Willpower, 8 Charisma and +4 drain dice from whatever origin, they’ll be at 17 drain dice. Let’s assume they’re also at 17 Summoning dice, which once again is quite doable.

First, the Summoning itself: There’s 2/3 chance to succeed, and half the successful summons will be at 3+ services. Plenty to butcher your way through whatever your GM throws at you.

Second, the Drain: 2/3 chance to take Drain, 1/3 chance to score 4+ drain, and assuming 10 Physical Monitor 1/31 odds at going unconscious (which means disaster). Those are rather excellent odds, since with combined numbers you have roughly 1/3 odds to fail generally. (More exact numbers would require a handwritten program to analyze the odds, but that 1/31 and a bit less than 1/3 odds mostly overlap so it still is ~1/3 overall.)

Without Edge.

If we bring Second Chance into the Summoning, failure is at ~1/32 and average services are past 5. And drainwise we’re suddenly at only 30% chance to get hit by ANY drain. 10+ odds are at ~1/3.000, 6+ at ~1/25 and 3+ at ~1/6. Let me repeat that: At the expense of 2 Edge, a player can score 5 services and take only 1P in drain from an unbeatable Force 12 Spirit. So all they have to do is make sure they have 3+ Edge, summon this at the start of a run and make it tear down the enemies without having to sweat at all.

It gets worse. Let’s assume the Shaman has +4 Charisma, +4 Willpower, 2 Initiations and a Force 3 Centering Focus. That’s 26 drain dice, which means that unedged their odds are worse but they still are at ~1/5 for 3+ drain, ~1/30 for 6+ and only ~1/150 to get hit with 10+. And even IF this worst scenario hits, they can still Second Chance it.

So unfortunately, Drain is not enough of a deterrent by itself against Oversummoning. Which means that Oversummoning is a high threat to the game balance and any player who so desires can greatly upset the game and ruin the fun for all. Now normally the social contract applies, but what if you cannot depend on that?

That’s where we grab back to SR4 Street Magic. In there was a rule, not an optional rule but a simple core rule, where Oversummoned Spirits always resisted with Edge. Back then their Edge equaled their Force so they resisted with Forcex2 exploding dice. Needless to say a Force 12 Spirit would utterly butcher you in drain.

In SR5 the Edge has become less, it is now half their Force. Which means an Oversummoned Force 8 Spirit could either have 8 rerolled dice (averaging 4.44 hit) or 12 exploding dice (averaging 4.8 hits). In other words, a Force 8 Spirit using Edge would be better off than that Force 12 Spirit we used in the previous scenarios.

Let’s take a look at 12 exploding dice. Against a Force 12 spirit our 17 second-chanced dice meant massive drain reduction, with only 1/6 chance to get hit with 3+ drain and zero odds at actually dying. With Edge-use the Force 8 Spirit is already at 30% and 1/140 death chances for an unwounded Body 3 Mage. So the Force 8 Spirit is significantly tougher than the Force 12 was.

Meanwhile, 26 rerolled drain dice versus the Force 12 Spirit would become ~1/3 at 3+, ~1/6 at 6+, ~1/16 at unconscious for Body 3~4, and ~1/80 death chances for a Body 4 mage. Definitely odds you do NOT want to frequently take, no matter how good you are.

Disclaimer: Said math was done with an emulation of an exploding die which cannot explode more than 4x, so only 5 hits per die are possible. However, this manages to emulate an exploding dice to near-reality at the point where the full numbers would differ only past the decimal cut-off.

MATH DONE

In short, Drain is unfortunately far from enough of a balance factor against an eager Oversummoner, and even maximum-Force Spirits are perfectly doable for someone who tries, which greatly upsets the game balance.

By making Spirits employ Edge against the Oversummoning, this is balanced out better and said mechanism will not harm normal Conjurers in any way. And when a player can make a good argument that in a specific situation the Spirits may be willing to help, the GM can always waive the Edge use for that one situation where it comes down to the line.