[carlosib]

I used lots of communions in my last game and i learned that you have to take in consideration the objective of the communion at the moment of the setup. Communions are rather flexible and they allow some nice strategies, but if you lose the focus and try to cast a bit more than it can handle, then you can have some nasty results.
Just one word of advice, to get it right and dont lose a game to a bad planned communion always try it before in a SP test game. You'll be surprised of how many times you'll blow it just for a little detail and be glad you didnt test it in a MP game.
(I've been hours trying to setup communions to cast Fog Warriors and Doom + Bone Grinding x 2 as Ermor)