If you are on a level with a transfer creature special and a resurrect creature special, you can transfer your creature, he will become dead in the games eyes then you can resurrect him, that way if you have more than one resurrect special, you can have more than one of the creature you transferred.

You can also transfer a creature to the ‘next’ realm, then hit escape, quoting the level, go back in, then you will start that level with that creature.

This was true for the original, not sure if it’s changed in FX