Grimrock

Is there a way to trigger a set of events by checking the party has cast a certain spell at location x,y?

ie like when you summon the vines.

The vines summon is done via a usable item (prob. through the onUseItem-hook, and checking party location)
If you want to do the same thing with a spell you'll prob. need to go through the onCastSpell-hook:

PartyComponent.onCastSpell(self, champion, spell)

That's kind of helpful, but I'll be doing it without an item, ie needing a way to check party casts the spell when stood somewhere. it's how I do it without a trigger being used etc.