I've actually always been tempted to do something with traps, maybe inspired by some video game stuff like the Witcher or D3's Demon Hunter. But, I can never find a way to really make them work. The problem I have is that it ends up being very swingy. It's kind of like buffs in D&D that way: if you have time to prepare the battlefield (i.e., seed it with a ton of traps) then you roll most encounters, if you don't, then the abilities just sit idle on your sheet.
That's been my challenge with them anyway. For balance, I'd kind of like to compare them to less flexible summoned creatures.