Communions: The Battlemage Suicide Pact Explained (A Modern Communion Guide) Thread - Dominions 3: The Awakening

Hello all. I hear you want to learn about communions. A communion is an in-battle path and fatigue management tool for mages. Their reputation as complicated is well-deserved, but they follow a basic set of rules that anyone can pick up.

The Basics

Before we begin, understand that there is one communion per side per battle. That communion can be joined using Communion Master, Communion Slave, Sabbath Master, Sabbath Slave, the items Crystal Matrix or Slave Matrix, or by being a MA Pythium Theurg Communicant. All these things join the same single communion.

1. The first thing to understand about communions is Masters get a path boost and reduced fatigue based on the number of slaves in the communion. Slaves do not get this path boost. When a Master casts, the reduced fatigue is distributed amongst the Slaves. If you load up on many Masters or high fatigue spells this can easily kill your communion Slaves. The formulas for this are complicated, but the important part to remember is that Masters get +1 path boost every power of 2 Slaves.. so 2, 4, 8, 16, and so on. The path boost and fatigue reduction is what makes Standard Communions tick.

2. The second thing to understand about communions is self-buff propagation. If a Master casts a spell that targets 'caster', all Slaves in that communion also gain that self-buff (but note other Masters do not). Path-buff spells like Summon Earthpower, Power of the Spheres, etc count so long as they target 'caster'. Note that targeting 'caster' is a specific type of target. It is NOT the same thing as casting a spell with AoE1 at yourself, like in the example of Body Ethereal. This is half of what makes Reverse Communions tick.

3. The third thing to understand about communions is caster order. If any Master casts, all Slaves that act after that Master can not do anything in that round. Caster order is determined by commander ID, a semi-hidden stat set upon unit creation (recruitment, summoning, etc) that cannot be changed by any means. Your commanders are listed in ID order on the map and army placement screens already. So if you want Slaves to cast (and you don't necessarily want this, remember they don't get the path boost and they're already taking heaps of extra fatigue), then you must make sure those Slaves are before any casting Master in caster order. This is the other half of what makes Reverse Communions tick.

Memorize the three points above, because every single type of communion uses those points in some kind of combination.

Basic Communion Types

A Standard Communion uses the path boost to Masters (+1 per power of 2 slaves) and fatigue reduction to help the Masters spam spells or cast spells they otherwise couldn't. The Slaves suffer the lion's share of the fatigue, which ends up converted into hitpoint damage once it reaches 200. Finding the right ratio of Slaves to Masters is difficult and depends on the paths of both Masters and Slaves, the spells being cast, and abilities like reinvigoration. But your path boost is not limited by anything other than how many mages you have available.

A Reverse Communion uses self-path-buffs and other handy buffs cast by Masters to boost the paths of the Slaves, and then uses the Slaves to spam spells or cast spells they otherwise couldn't. Summon Earthpower/Water Power/Storm Power/Phoenix Power/Strength of Gaia and Power of the Spheres mean you can boost all slaves a max of +2*, and you can also propagate precision (Eagle Eyes) or defensive buffs like elemental immunity. It relies on the Slaves going before the Masters in caster order, or having the Masters not cast after they finish setup. For example equip the masters with bows and give them Fire orders, or have them Retreat. Much of the time however, you will simply pick Slaves and Masters such that all the Slaves go before all the Masters.

*Technically Hell Power is also a self-path-buff, but it also has a 20% chance of attracting a horror per unit with the buff per battle round. Using it to reach +3 is suicidal. Highly NOT RECOMMENDED except in extremely exceptional circumstances.

Every single type of communion is a combination of the two types above. If past this point things in the guide get too complex for you, all you really need to know is The Basics and the two Basic Types.

The advantages of a Reverse are that other than one or two Masters, you can involve all your mages in casting, provided they have appropriate paths to cast the spells you want to begin with. The risk of the Masters killing the Slaves through distributed fatigue is also very low.

The advantage of a Standard is that you can buff beyond +2, and that mages who don't have appropriate paths to begin with can still contribute in a reduced way as communion Slaves. However the risk of Masters killing Slaves through distributed fatigue must be managed, if you care about that.

Advanced Communion Types

Double Communion - A combination of a standard and a reverse communion; you have several Masters all at bottom of the list and intend both Masters and Slaves to spam spells. Commonly used in communions where all the participating mages are identical and as such it doesn't matter who is Master and who is Slave. Some people just call this a Reverse Communion, but the differentiation is the Slave:Master ratio, a double will have a Slave:Master ratio closer to a standard communion, whereas a reverse communion will have around 2 Masters.

Double communions rack up a lot of fatigue on your Slaves. Going double is a good way to turn a normally safe reverse into a suicide pact, although many experts claim it's perfectly safe. But it's also a good way to cast a powerful enchantment on a Master while also getting a decent path boost through propagated self-path-buffs for your evocation spammer Slaves. The more Masters the riskier a double gets.

Linebacker Communion - A reverse communion where the Slaves are buffed by the Masters for melee combat rather than spellcasting. Can be used to propagate buffs outside the Slaves' paths, like Phoenix Pyre, Soul Vortex. Please note that Slave Matrices can not be used to propagate buffs to a non-mage, for some reason. You may be able to get around this by making your non-mage into a mage by empowering in blood.

Linebacker communions can receive a lot of nice defensive buffs, but offensive buffs are much more scarce. It's common to equip Linebacker communion Slaves with forged melee weapons to increase their offensive potential. Also, you won't turn fragile mages into combat badasses; you need to start with fairly sturdy mages like R'lyeh's Starspawn Priests. Also see the note in 'advanced tricks' about propagating item buffs.

Micro Communion - A standard communion with only 1 or 2 Masters and only 2 or 4 Slaves, built specifically to let a Master cast a single spell he otherwise wouldn't be able to, usually a battlefield enchantment like Darkness.

Blood Communion - By using a Master with ranks in blood, a communion can incorporate the self-targeting spell Reinvigoration, which removes 100 fatigue from 'caster'. Although convincing a caster to cast Reinvigoration is difficult, removing all fatigue from all your communion Slaves is absolutely incredible. However, the spell AI will sometimes refuse to cast Reinvigoration, even when scripted to. Our best guess as to the cause of this unreliability is that the spell AI will only cast Reinvigoration if the caster has a certain minimum fatigue. A B1 spamming Reinvigoration usually works; he will always have some fatigue since casting it adds 100+enc and removes 100. A B2 will zero his own fatigue since casting adds 50+enc and removes 100. This is particularly relevant to communions because all you need is two slaves to boost a B1 to B2, so in practical terms every communion will run into this problem. The workaround is to cast Reinvigoration on different Masters in concurrent rounds, never the same.

One use of a blood communion might be using a single Slave and a single B1 Master. The Slave is the primary caster, it needs to go first and cast a high fatigue spell, like Master Enslave. The Master goes after and casts Reinvigoration for each of the 5 scripted rounds.

Turbo Communion - A standard communion with a lot of Masters and typically 2 to 4 Slaves, where the Slaves are kitted with regeneration or reinvigoration. The Masters have their fatigue cut in 1/2 to 1/4, the slaves don't die because of the regen/reinvig. Methods include using high hitpoint Slaves with innate regeneration/propagated Personal Regeneration/Mass Regeneration, propagating Soul Vortex with regenerating units on Guard Commander, propagating Pain Transfer, or regen/reinvig items. Regen works because after the Slave hits 200 fatigue, additional fatigue is converted into damage at a 10 fat = 1 dmg rate. This communion can be costly and is tricky to plan, but massively extends firepower and number of casting rounds of your masters. Blame #dom3goons and #Dominions for inventing this one.

Superman Communion - A standard communion with a ton of Slaves and only 1 or 2 Masters, focused on casting a single very powerful spell over and over. Master Enslave is the classic. The old Baalz guide mentions this one by name, personally I just call it a Standard Communion.

Suicide Communion - For the purposes of this guide, a suicide communion is a communion that specifically fucks the battlefield so that "nobody wins". Common methods: Hell Power, Phoenix Pyre followed by Blink or Personal Flight, etc. A suicide communion is not a good idea, but some people love their bad ideas so be my guest.

The old definition of a Suicide Communion was a standard or double communion in which the Slaves are intentionally expected to die from fatigue.

Delay Communion - This is the only communion that uses a different mechanical trick than everything else. That is to say, when a caster skips its battle turn for any reason, including communion slaves whose master has already cast that round, the script is preserved and not advanced.

So a Delay Communion is basically multiple Reverse Communions or Double Communions, interspersed in the casting order with Communion Masters who retreat/charge forward & die/fire a bow at the point in their script when you want to trigger the Communion Slaves below them. When they stop casting, the slaves below them in casting order are now free to act, and do so according to their original script. Since a slave can also be a master, you can stack this up as many times as you like.

You can use this trick with a single master and your main battlemages as communion slaves to delay your casting for 5 rounds (to counter people who use Guard Commander tactics to avoid a normal 5-round script). Or you can stack up multiple reverse communions with a master between each to deploy a steady barrage of high-fatigue spells instead of unleashing them all at once. This is probably not very effective with damage spells, since you usually want damage to be front-loaded, but might be very effective with debuff spells.

Advanced Tricks and Trivia

* Did you know that a mage can never exceed 200 fatigue with a spell that mage casted itself? Even with a super-high-fatigue spell, like Master Enslave (800 fatigue), even if the mage already has 99 fatigue, you'll be set to 200 when you cast instead of exceeding it. The only way to exceed 200 fatigue and therefore take hitpoint damage is from external sources. In communions these external sources include fatigue distributed to Slaves from Masters casting.

* Fatigue over 200 is converted to damage, at a ratio of 10 fatigue = 1 damage (*untested, going by memory here). This can easily kill your slaves, since every single master will be adding to this every single round. But the ratio itself is absurdly good, in my opinion. You can propagate Personal Regeneration to Slaves or cast Mass Regeneration, and they will basically never die, especially if they have more-than-human hitpoints to begin with. The best version of the Turbo Communion uses this trick, despite the slaves reaching 200 fatigue.

* Thanks to the Slave fatigue formula, a 1-Slave communion is completely pointless for fatigue reduction; the Master will take full fatigue, and the Slave will also take equal fatigue. HOWEVER it is still excellent for propagating buffs, in particular a Reverse/Double with a Slave as the primary caster and a B1 Master spamming Reinvigoration.

* A Reverse is an exercise in scripting efficiency management. If you've ordered the casters so the Masters are at the bottom, one trick is to keep the Slaves out of the communion round 1 and cast a normal buff, maybe one that doesn't target 'caster' like Body Ethereal. Do have the Masters join round 1. Round 2, have the slaves join, and have the Masters propagate 'caster' buffs like Power of the Spheres. This way you get an extra buff out of the slaves in the same number of rounds.

* A common use of the Crystal Matrix is to use them on the masters in a Reverse or Double. Your Slaves still cast Communion Slave, but then at the bottom of the order the Masters can now cast the self-buffs on round 1. Then your Slaves get 4 rounds of spamming whatever you wanted. If you had to cast Communion Master round 1, then the self-buffs on round 2, you would have lost a round worth of spells.

* Another use of the Crystal Matrix is in micro communions when getting a certain spell up round 1 is absolutely critical, like Storm to stop enemy fliers.

* Certain buffs from items can be propagated through communions, if those buffs are spells that target 'caster'. Not act like spells, literally ARE spells. Go to Mod Inspector and search item properties for 'onebattlespell', keeping in mind that only spells with a target of 'caster' will count. In Mod Inspector get this to show up by checking "More Info" then clicking through to the spell description.

Furthermore, buffs from items will only apply to units that have joined the communion at the very start of the battle. That means Crystal Matrix on the item holder, and propagates to those with a Slave Matrix or Theurg Communicants only, and furthermore they are still affected by caster order. Think of all these item spells including the Matrices' Communion Slave/Master as being cast on 'round 0'.

Also note that some of these spells are identical to casted spells. For example, a Crystal Shield can be used to give Power of the Spheres, but you won't be able to double up by casting Power of the Spheres again during the battle.

* Also applies to item spells that cast every round and target 'caster', like Sandals of the Crane. Follow the Mod Inspector link and search item properties for 'autocombatspell', then enable "More Info" and look at the spells to see if they say 'caster'. I think the only such item in the unmodded game and most mods is Sandals of the Crane.

* Propagating Phoenix Pyre is a great way to turn a group of mages, even ones reasonably spread out, into a bomb that wipes your entire own army and mage corps. And Phoenix Pyre is often cast off-script by fire Masters. Possible contingencies: Propagate Invulnerability as well, spread out your mages.

* A mage can be both a Communion Master and a Communion Slave. The mage doesn't count as a Slave when he casts, and if a different Master casts before him in the caster order he will be forbidden from acting.

* As noted under Delay Communion, slaves that skip their turn due to a master casting do not advance their scripting. And since a slave can also be a master, as above, you can use masters as 5-turn delay blocks to delay the activation of the script of the slaves under them.

* The other common reason to skip one's battle turn but not advance the script is if you're out of fatigue; when you get back into fatigue you're back on the old script where you left off. You can use Reinvigoration through a communion to use this effect for a communion slave in a Reverse or Double Communion, although it's of quite limited use since you'll need to be casting extremely high fatigue spells AND wanting to delay. Front-loading spells is usually better, since it means you're more likely to rout the enemy.

* There are many more tricks and trivia, others may mention them in this thread or in the dom3mods version of this thread, which has some very insightful commentary.

Communion Math

Master Path Buff = log2(n) rounded down, where n is the number of Slaves at the time of casting
Master Fatigue = [(spell base fatigue) / (1 + extra paths) + (spellcasting enc)] / (# of slaves)
Slave Fatigue = no one actually knows this, if anyone claims to without a battery of test data they're mistaken. See this thread. If you do have a battery of test data please share.
Slave Fatigue, incorrect formula that provides an approximation = (master fatigue) * (2^(master path level without communion path boost - slave path level without communion path boost)[min 0.5, max 4])or alternately: sf = mf * 2^clamp(ml - sl, -1, 2)

Edited by: The_Demon

Another excellent Codex entry, I see.

Excellent one indeed. I thought i knew well communions but never had the idea of delaying them past several turns. Very nice

Until I wrote the guide, I never had that idea either, but Calahan spilled the beans in the dom3mods thread and now we all know

Thanks for the great guide!

I have two practical questions, which I'm not sure if they are related to any of the concepts explained here or not.

1. I tried to cast fog warriors in two battles, with an A3 Oreiad + crystal matrix, and ~6 mystics as slaves. I calculated paths as be 3 base + 2 communion. The Oreiad had 4 air gems, 3 for the spell and 1 for halving fatigue. In both cases, she decided to cast arrow fend instead. Is that because of fatigue, as the slaves didn't have air? Casting fire storm later in the same round was no problem, but all slaves had at least F1. In both cases, the enemy army was quite sizeable, so the AI should have been ready to invest some gems.

2. I tried a communion with the masters casting phoenix power and elemental fortitude for 50+50=100% fire resistance, with fire helmets for the masters and fire snakes as blockers. Then raining down battle-wide fire evos like fire storm. Unfortunately, the slaves stayed ad 50% fire resistance, and all burned to cinders. Is that because the spells are not cumulative, because one of the spells is not a real "target:caster" spell, or is there another mechanism at work?

I killed more of my communions than you could shake a stick at, but in most of the cases, I at least understand why they died. Not so here...

Brihaspati wrote: 2. I tried a communion with the masters casting phoenix power and elemental fortitude for 50+50=100% fire resistance, with fire helmets for the masters and fire snakes as blockers. Then raining down battle-wide fire evos like fire storm. Unfortunately, the slaves stayed ad 50% fire resistance, and all burned to cinders. Is that because the spells are not cumulative, [...]

That's exactly it. Spell effects are never* cumulative. So two spells giving elemental resistance don't stack. Neither do Iron Will and antimagic for example. This has the side effect that it's impossible to make non-commanders immune to an element unless they have native resistances.

* There is one exception, but I don't recall which one. Which is a sure sign it's not important and you can safely use the above as your guideline.

I have no idea about your first question. That doesn't comform to my understanding of spellcasting AI behaviour at all. Unless the casting Oreiad already had mistform from another source (ie., she cast mistform before trying to cast fog warriors) perhaps? That would be similar to refusing to cast area resistance spells due to being immune to the element him/herself. But I'm not sure the same rule applies to mistform.

Edit: you mention a crystal matrix. I'm assuming your slave mystics came before your Oreiad in the casting order, and thus had already cast Communion Slave before the Oreiad tried to cast Fog Warriors? (Or at least 2 of the mystics did. That would raise the Oreiads effective casting lvl to 4, meaning she's capable of casting Fog Warriors with an extra gem.)

Edited by: Amhazair

Thanks for the reply, and your sincere effort to understand what a noob might think. Probably my mistake is even weirder than the ideas you already had :-)

The non-cumulative spells make sense. It felt almost too easy to create a mobile hell, and that was because it _was_ too easy. At least the slaves dies for the greater glory of Arcoscephale, and took a bunch of mages and a Tarrasque with them.

I neither cast mistform, nor had any gear except for the matrix on the brave Oreiad. I also made sure she cast another spell (Strenth of Gaia) in round 1, so the communion had time to get together. In both communions, one of the masters was the first unit in spellcasting order, to ensure that the slaves won't find creative ways to kill themselves. It is my own job to find creative ways to kill my communions.

Edited by: Brihaspati

Here is a thread that doesn't explain your Fog Warriors problem, but delves into the issue:
Z7.invisionfree.com

That said, according to our best understanding Fog Warriors from an A3 master with 6 slaves should cast successfully. So I'm not entirely sure if this is the same problem as what you had; as you can see the gem use issue in communions hasn't yet been thoroughly tested.

Edited by: The_Demon

Nice link, it's good to know that you can use more than one gem for fatigue reduction. I might try some extra gems and see what happens. I have a feeling that the missing air on the slaves is part of the problem. The second master (F2+phoenix power) was able to cast fire storm (5F, 500fat) after the A3 Oreiad refused to cast fog warriors (5A, 300fat) both on round 2, and they had roughly the same fat. But all slaves hat at least a base of F1, plus phoenix power.

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Jul 22 2013, 8pm
I wanted to do some testing, but cannot reproduce the behaviour in SP. A3 Oreiad, 4 gems, 6 slaves, and I get Fog Warriors all right. Will probably have to have a much closer look at the battle in the MP game to understand what happended. No doubt some truly noobish mistake. One of the nastier side effects of playing Dominions is feeling pretty dumb most of the time.

Edited by: Brihaspati