Make lichform prevent itself, since undead can't tmut

[genericpseudonym]

Entering lichform makes you count as undead, which should make you totally unable to use shapechanging magic.

Of course this should cancel any ongoing transmutations as well, so ideally entering lichform will make you ineligible for spells like necromutation and thus immediately cancel any such effect.

[dynast]

What if necromutation was irreversible instead?

[PleasingFungus]

if necromut was irreversible, it couldn't be a spell.