Guide: Guide to communions

[Baalz]

Alright, seems like every couple months a new thread with questions about communions pops up so I figured I'd write a guide about communions, answer the common questions and go over the basics of how to use them effectively. Communions are potentially very powerful, potentially very dangerous, and definitely kinda confusing.

The basics.

Communions (and their interchangeable, less well known blood brother Sabbaths) are a way for mages to work together to become greater than the sum of their parts. The slaves both boost the magic power of the masters and soak up the fatigue of the spells cast resulting in masters who can cast big spells much longer than otherwise possible. Because of the fact that they keep soaking up fatigue after exhaustion - all the way up to 200 fatigue at which point they start taking damage and quickly die, it is often the case that a mismanaged communion causes catastrophic loss of mages even when you win. Many the player has sworn off communions after watching a dozen mages perish as Armageddon is opened up on the terrified and fleeing PD. In Dominions, bad luck can always render any carefully laid plans asunder, but understanding how to use communions will result in them being much more useful and much less dangerous (to you, hopefully they're quite dangerous to your opponent).

First it's important to understand the basic mechanics of the communion. Slaves boost the power of both slaves and masters inside the communion by 1 per power of 2. This means +1 at 2 slaves, +2 at 4, +3 at 8, etc. The masters are boosted in all paths which they already have, while the slaves are boosted in all paths whether they have them or not. The slave power is important for calculating the fatigue they receive for spells cast by the master. The specific mechanics of how fatigue is parsed out is not entirely clear, but roughly slaves will receive fatigue as if they cast the spell themselves (which is why the power level is important), divided by how many slaves there are. Encumbrance is not added to this calculation and significant extra fatigue is accrued if the slaves could not cast the spell themselves after the communion boost - another reason the slave power is important. The communion bonus does not show up on the character sheet, but it is effected by buffs. This means that so long as there are at least two slaves, all slaves will benefit from such spells as phoenix power for the purpose of soaking up fatigue. All commanders resolve their orders in the same order that they're listed in the strategic screen from top to bottom. This is particularly important to note for communions as any slaves acting in a turn sequentially before any masters act will be able to cast spells (and indeed will do so by default). This can be a really good or really bad thing (see below), so make sure you anticipate it. Note, there is no known way to alter the order the commanders act in, just to anticipate it and change which ones will be slaves and masters (and which ones you bring to battle). Note, all spells are resolved before movement or archery, so the order the commanders is only relevant for resolving spells - slaves will not be able to take any action other than spells regardless of what order they come in if any master casts a spell.

Here's a good example about how fatigue is split:

MaxWilson said:
3. The short answer is that fatigue is split between master/slaves BEFORE adjusting for path levels, but slaves also get the communion bonus to their paths for these purposes. If a spell is cast which requires D4 and 400 fatigue, and there are 4 slaves in the communion all with no Death paths, each slave and the master will take 80 fatigue, adjusted for path levels and drain (plus fatigue, for the master). With the +2 communion bonus for 4 slaves, each slave is D2 casting a D4 spell, and since they are 2 levels short they take triple fatigue damage or 240 fatigue (which I think means 40 fatigue gets converted to 4 HP damage). If you are N levels short you take (N+1) times fatigue, if you are N levels over you take 1/(N+1) times fatigue.

Putting together a successful communion is a lot like baking. You've got several different basic components which need to be properly balanced, and a few optional extras which can be used to add an interesting twist if you want. Just like baking, you can't stray too far away from the correct ratios or the bread won't rise resulting in best case reduced effectiveness of the communion, worst case a bunch of dead slaves. The basic components of course, are the masters and slaves, and choosing the correct ones to use is not as easy as it first seems. First, you've got to decide what type of thing you're baking, is it bread, or cookies, or a cake? There are several different types of communions, here are a couple recipes. Once you become familiar with them you will be able to tweak them without unbalancing the important factors and come up with your own recipes.

Classic communion - This communion is intended to rain down mid-line evocation spells in a never ending barrage. Masters should have an elemental path and you'll want to script something like falling fires, falling frost, magma eruption, thunderstrike, acid rain, blade wind or gifts from heaven. Slaves will either need one level in the same path or one of the masters will need to cast power of the spheres (or phoenix power, etc if all your masters are the same path). The really important thing to keep in mind with this communion is critical mass. You need to have *at least* 8 slaves, 10 is much safer to have a buffer against those stray arrows. Outside of that, as you add masters make sure you have more slaves than masters. 14 slaves, 12 masters is fine*, but if you're short on mages you'll want 10 slaves and 5 masters. The * is because you'll need to add a few extra slaves if you're spamming particularly fatiguing spells like Thunderstrike. Your masters will have +3 to all paths, which really helps those spells which scale with mage power. Your slaves will be at least level 4 after the boost, which means they should be taking only 1-3 fatigue or so per spell that is cast as the spells you're casting all have requirements of 3 or under and fatigue in the 30-50 range - this is important in order to keep your slaves from accumulating fatal fatigue. No worries as these are the spells the AI will choose once your scripting expires, and you should be able to go 15 or so turns before slaves start dying, making this quite a rare occurrence (not much stands up to 10 turns of such a barrage, you'll generally have won or lost by then).

Reverse communion - 2 or 3 masters then as many cheap slaves as you can muster. Your masters will cast power of the spheres then whatever other booster is appropriate (phoenix power, etc). For air spells you can use the third master to cast storm so that air power is an option. Now, all your slaves have been boosted 2 levels, so they can cast fun things like falling fire, thunderstrike, etc. Even lowly S1 mages are now capable of Soul Slaying. The fun thing about this one is it's a great way to use all those cheap researchers you've got with no other preparation. Leading a fight with three rounds of 10X Falling Fires makes quite a difference considering how cheap the mages are. Note, this communion takes advantage of one of the quirks of the communion, the fact that slaves can cast spells so long as they act sequentially before all masters in the turn sequence. Commanders resolve their orders in the same order that they're listed in the strategic screen. If for whatever reason you're not comfortable trying to get this order right you can have the masters retreat after casting the buffs - the buffs remain in effect. Note, the communion bonus does not affect slaves casting by themselves, only the buffs the masters cast help. Apparently the slaves are acting by themselves outside the communion.

Linebacker communion - 3 or 4 masters with varying paths and at least 10 slaves. This communion takes advantage of the fact that self buffs which affect a master also affect all slaves. The masters will cast as many self buffs as possible before the slaves wade forward into melee. This tactic works best with slaves that have more hitpoints and a good attack (like starspawn or vampire counts), but even just passing out frostbrands to your average poindexter before he is buffed with invulnerability, mistform, regeneration, quickness, luck, fire shield, astral shield and breath of winter - well, there are worse uses for a slew of S1 mages. Note, for this to work it's important that you have a sufficient number of slaves, otherwise the slaves will rack up too much fatigue during the buff cycle and be worthless for combat. Also, the slaves will not move or fire if any masters cast spells that round, so you can either have the masters join in the melee attac, retreat from the battle, or equip them with bows and script them to fire after all the buffing is done.

Kamikaze communion - 4 slaves as cheap as you can manage and 4-6 masters. This one is straightforward enough, the point is to boost the masters up two levels to give them access to the next tier of offensive spells (ie, giving A1 mages the ability to cast Thunderstrike). As the name implies, the slaves are not expected to survive. This can be a good way to pack a lot of firepower in a pinch.

Superman communion - The numbers on this one vary depending on what you're trying to accomplish, but the idea is to have a whole bunch of slaves and only one or two masters casting those really devastating spells. The classic example of this is Master Enslave communions, though there are other good choices for more modest uses like flaming arrows, fog warriors, darkness, etc. The important factors are that there are enough slaves and that the handful of spells which are cast are devastating enough to make the opportunity cost worthwhile of all these mages doing nothing else.

Alright, there's some basic recipes for your book, obviously you can start mix and matching them as you become more comfortable. Now for the optional twists previously mentioned.

The blood spell Sabbath Master is equivalent (and mutually interchangeable - you can join a communion by casting Sabbath Master) but functionally there are two big differences. The first is that Sabbath Master costs 100 fatigue, so casting it with a B1 mage will result in a pass out once you account for encumbrance. What makes up for this in a big way though is that nice little blood spell reinvigoration. If a master casts reinvigoration not only does it remove all his fatigue, it removes all the fatigue of all the slaves. For this reason strategic use of a single blood mage can as much as double the effectiveness of your communion.

Crystal/slave matrixes. These magic items allow non astral/blood mages to join a communion (note: they must still be mages of some type). The potential uses of this in combination with the linebacker or reverse communions should be obvious. One note of caution however, because of the fact that slaves rack up fatigue really fast if they don't have the paths for the spell the master is casting it's very important to have enough slaves to compensate for this if masters are casting spells which the slaves don't have paths in.

Keep in mind penetration goes up with the mage's power and sometimes extra penetration can be worthwhile even if you're not enabling extra spells. Have that S9 pretender lead all those S1 researchers you have in a communion before spamming enslave mind. It beats whatever the heck S1 mages would otherwise be casting.

Phoenix pyre can add an amusing twist to the linebacker communion as it can set off a devastating chain reaction. Expect this to be a fairly kamikaze move.

Some magic items cause their effect by autocasting a spell at the very beginning of combat such as a charcoal shield or crystal shield. These spells, if they're self buffs will effect slaves who are part of the communion so long as the item is worn by a master who is in the communion. Since the timing on this is such that the buff is cast before anyone can cast master/slave communion, this generally only effects people wearing crystal/slave matrixes (though pythium's communicants are an exception, and there may be others).

Hellpower is an interesting spell in combination with Sabbath, but rather difficult to use effectively. A master casting hellpower will result in every slave being effected by all the effects of hellpower, including being horror marked and having a chance of calling a horror. Obviously you seldom want a bunch of people calling horrors immediately after all your mages have been horror marked. This can be useful in two situation though. The first is if you are fighting a SC (or really anybody) who has already been seriously horror marked (if you're particularly baalzy, you might try to horror mark them the same fight before casting hell power) - horrors will attack the most horror marked units first. The second situation is a kamikaze linebacker move where you uber buff the slaves then don't care if they die. This is pretty wasteful though unless your slaves are tough enough to survive a couple AN hits from horrors. I have used this tactic successfully with LA Ulm's vampire counts (2b 2d), resulting in a dozen uber buffed, life draining, flying thugs...who happened to be immortal so no worries if they died. The nice thing about hell power is it not only increases magic power, it increases attack, defense, strength (hitpoints, I don't remember) so it's particularly useful in this case. Note, your slaves are going to rack up horror marks when you do this even if you win the fight, so use it sparingly even with immortals.

DrPraetorious said:

Communion masters generally carry valuable gems, possibly penetration boosting items, and seldom have to worry much about fatigue, obviously. So it's generally a good idea to protect your investment (vs. stray arrows, for example) by putting them in some armor.

This also goes to the question of how to protect a valuable communion if you are very communion dependent (for example, as Pythium or Ermor or Bogarus).

* Rune Smashers, Eyes of the Void and Spell Foci are all great for masters casting Shadow Blast or groovy stuff like master enslave.
* Masters spamming elemental attack spells want boosters, not for fatigue reduction, but for increased damage and/or area of effect. This is obviously true for most of them (note all the +s in the spell description) - what most people don't know is that the fatigue inflicted by the secondary wave (which is area 9!) from thunderstrike is also air-magic-dependant, so if you can push your air magic up higher it becomes much more devastating.
* A communion matrix is often a good investment even for a communion master who has astral. +1 turn of spell casting is a huge advantage, and for a big-spell communion, it is not expensive.
* 50% resistance to fire and cold more or less assure that you won't go down to a murdering winter or flames from the sky. Various combinations of armor and misc items grant this, but fire plate and a ring of ice is probably the cheapest way to go.

In the late game, murdering winter/flames from the sky are a virtual surety. If you have the Forge, absolutely forge fire plate and a ring of frost for each and every slave.

Meglobob said:
I have been using communion slave, banishmentx4, stay behind troops on a big communion. It works very well vs undead armies and is no real danger to your slaves because banishment is 0 fatigue. So why not cast it?

Works with any 1S 1H mage/priest.

An often overlooked aspect of the communion is the fact that it also buffs holy levels (as does power of the spheres). The flip side of what Meglobob suggests can be good - H6 priests spamming banishment are hideously effective at clearing out low level undead due of the exponential increase in effectiveness the power boost brings. You can even use crystal matrixes if you don't have astral priests, though keep in mind that they do need to be some flavor of mage for the matrix to work. No reason you can't, say slap a crystal matrix on a High inquisitor (3H 1F) then have lowly astral slaves boost him up to an undead popping juggernaut. Since banishment is 0 fatigue this makes a lot of sense to combine with a reverse communion - your buffed masters can banish away without fatiguing the slaves.

Sometimes it can be useful to pass out items which can "cast spells" to communion slaves so they can use them fatigue free (outside of encumberance), this can be a little dangerous though as you'll have to script your slaves to "cast spells" after your script runs out which means the AI might decide to cast something unexpected driving up your fatigue rather than the 0 cost item spell. Still, this works particularly well with standards of the damned because the life draining effect removes fatigue. Not cheap, but if you can manage to get one on each of your slaves you can have an effectively unlimited casting out of the communion on top of a slew of sniper slaves.