Void Walls and Moneybags
Void Walls. Difficult to use, as most maps just don't have the wall space to support throwing them up, but when they can be used can be a god send to your defense, giving you a place to just throw stuff in like a trash compactor, and spitting out coins, potions, and if you grab the upgrade, the occasional skeletal orc to distract and fight against your enemies.
Up until the latest DLC, Are we there Yeti?, there hasn't been a trap that can really shove or launch the heavies around. Anything of cyclops mage size or larger was mostly immune to the void walls as they simply couldn't be launched into it. Enter the spike wall, changing the name of the game for the heavies and flinging them about like rag dolls, even the massive earth elemental lord takes a bit of a flop when smacked in the chin by these spring loaded wall traps.
So in experimenting with trying to combine these two traps on the endless map that came with the Family Ties DLC, Servant Entrance, I found a most peculiar thing. The skeletons that pop out of the void wall retain the traits they had in life. A frost ogre launched in that returns as a skeleton still deals frost damage and stuns, a troll launched in stops degenerating and actually regenerates health making him last longer (in fact unless under heavy assault from the mobs he'll last indefinitely), a cyclops mage still casts his homing magic missle spell turning it on the orc horde.
The peculiarity does not end there however, this might not be an intended effect. Might even be called an exploit. While certainly this cannot be achieved on every map, its a bit of a random luck of the draw, Mr. Moneybags when launched in drops his big coin and returns as a skeleton occasionally. And when the skeleton Mr. Moneybags dies, he'll drop a second large coin.
Unfortunately the one screenshot I managed is rather poorly timed, you can only just make out the skeleton under the reticle.