There's definitely crazy engine stuff to be done there. Procession makes that set insane.
Procession-Fortress is a lab which gives you +4 actions and gains you a 5-cost card (and keeps the fortress in your hand). Procession-Cultist gives you +7 cards, gives out 2 ruins and gains you a hunting grounds in exchange for your cultist. Band of Misfits can be either a Procession or a Fortress depending on what else is in your hand. Procession-Armory puts Procession-Fortress on top of your deck, and gains you a 5-cost card in exchange for your armory.
Procession on, like, any card in that set is awesome.
I don't know how it would play out in 4-player though. In 2-player, sometime around turn 9-11 you can procession your way into gaining, like, EVERYTHING. And if you have a lot of fortresses and cultists, you're knight-proof - if the knight trashes a fortress, that puts it in your hand, if the knight trashes a cultist you do lose the cultist but you start with an 8-card hand.