[BewareTheBarnacleGoose]

That's a pretty good idea. What I dont like, though, is that, if the remote-summoned unit survives, then it gets to fight again in the next battle, which might make it too good. Or too weak, in the attempt to balance it.

I suppose a way around that would be to add the script from gladiators that cause them to "die" after 1 battle. Would that work?

A unit would also be visible, which would kind of ruin the "trap" feel. I suppose that adding glamor would take care of that, though.