Liche Form is a buff, not a polymorph. At least at current it is as such. When you posted this it may have been different.
I wonder if adding the relative items from ID would be too overpowered for the *blast skill? Too bad I know of no way to make it spawn random objects of a particular type rather than those specified in the mod. (I am presuming such a thing does not exist yet.) I mention ID because I suspect that is the single most common mod used here. (Except those poor people on the Mac version.)
One thing that I will never ever do is code a mod that requires another mod. Or RotDG. Not because it's a bad idea per se, but I just personally have something against creating something that forces you to use something else in order to use it.
Double polymorph not only an issue with radiant wizard since it can be triggered by becoming a werediggle. The carrot form will end before werediggle does, and when the werediggle form ends the game crashes.
