[rdonj]

Also what you were reading about was referencing reverse communions, as opposed to the ordinary communion. As a refresher, a reverse communion is where you use one or more masters to cast spells to boost the magical powers of the communion slaves and maybe cast a few buffs on them, and then the commmunion slaves use their newfound powers to spam spells they would ordinarily be incapable of casting. Because of the quirks of this method, whenever a master casts a spell any communion slaves who haven't cast yet in the turn are unable to cast until the next turn.

In an ordinary communion this is unimportant because it's mainly about boosting the power of the masters, and the slaves aren't necessarily intended to cast anything.