Do terrain effects work on minions and denizens too? At first I was playing the games as yes it does affect them for difficult terrain but no for lava (Flying of course would beat both).
I guess I am more concerned about the lava effect then. I could not find anything in rulebook specifically saying that it wouldn't affect the monsters but I think from a theme perspective it probably should not since it is their home after all.
Yes minions are effected by terrain just the same as heroes unless there is something on their card excluding them from its effects eg. Starfire is immune to fire.