The Tavern

Once you get Necromutation you want it active most of the time. You always want to extend it before it expires but this rarely has any tactical impact. It serves mostly to annoy the player having to recast it so many times. The holy vulnerability and lack of potion access is is motive enough for ending the ability sometimes. Necromutation should have infinite duration and N/A spell power.

If this is overpowered then increase it to level 9, which would fill a conspicuous gap in the Necromany school, and be thematically appropriate as the ultimate Necromancy spell. It would also result in people seeing more interesting miscast effects and add tactical decisions where you have to decide if you really want that potion when you might not be able to return to Lichform easily.

That is true for all transformations, just as is was before for (old) repel/deflect missile. And all the other charms.

FR: Remove Necromutation as a spell, turn it into the capstone gift of Kiku or Yred or both. Permanent and irrevocable. Would need to reform player confusion, but until that's done, Necromutation should grant clarity.

I suggested that once. The response was, let us say, non-enthusiastic.

An easy solution for Necromutation is to make it start expiring only with monsters in view. So you don't need to cast it before entering a new Pan level and it does not interrupt autoexplore.