Honestly, there are nigh infinite "tricks" available. You'd need to tell us more, such as your players' facility w/ the rules, the sources they have available, how frequently they frequent this forum (
) stuff like that.
I am one of those communication type RPers, so I'd probably just tell them what sorts of horrors you expect them to unleash. I'm fairly permissive, so if you say to them "I expect you guys to be as badass as a solid core druid, but don't make me want to tear my hair out w/ annoying bits like scry & die and the wish economy," I think you'd probably be in good shape.
