Dungeon Master Forum

A new problem has arisen from the deep:

I created a new object that can cast a spell. I want the spell to exchange the monster hit by it (and only that one) for another one. The first monster is specially designed for that purpose and has to be invincible, so I can't work with the damage option or something like that.

Does anyone have an idea how to construct that thing?

Use SWAP.

This kind of thing is covered in my editing guide. It's a little out of date, but you'll still find an explanation in there.