In terms of other trap ideas, here's some OOC thoughts:
-Try and block off the cube's path with as much rubble as the vamponies can carry, it may have to slow down to dissolve it all.
-Get anything that can burn. Proceed to make a bonfire just a bit down the left passage where the vamponies came from. Laugh.
-Make a second bonfire just beyond the first. Laugh harder.

I could think of more, but it's getting late over here. Sandy, what do you think?

~glurggkk~

Good answer.