There are summon points, which you use to "buy" different troops during battles, the ones you unlock during game.Aswell you use those points to cast some magic. So you buy and send to other side to smash the gates. There's small cooldown for each different troops to summon/resummon.
There's also small events that u need to run from pursuers atleast in first game, not sure whats new yet in this one.
Game is fun
here's gameplay