It's your choice to summon. And I'd say a minimum of three turns to summon, more depending on how powerful the summon is.

Helpful Tips: Remember that the Godmodder is also capable of summoning powerful Godmodder Bosses to his side as well.

Also, I'm thinking of having "sidequests" of sorts, and building a story so it's not just a bunch of people attacking the Godmodder. What do you all think? Like? Dislike? Also, any ideas?