it's your sister Cheryl!
I work for Petersen Games. AMA
Once you unlocked this spellbook. Is it optional then?
Or do you have 2 spawn a acyolythe or wendigo, if a enemy is killed in a fight.
Every Spellbook and ability is optional, unless it reads otherwise on the text of the ability.
However, it's generally desirable to us Cannibalism, as it's a free Unit!