Is there a way to change a cantrip spell type to Necromancy in order to fulfil the requirement of the Death Domain Reaper ability for Clerics?

Question

The Death Domain Reaper ability says:

you learn one necromancy cantrip of your choice from any spell list. When you cast a necromancy cantrip that normally targets only one creature, the spell can instead target two creatures within range and within 5 feet of each other.

Unfortunately as far as I can tell, there are only 3 single target offensive Necromancy cantrips:

Chill Touch, Sapping Sting, Toll the Dead

Are there any class, feat or racial abilities in the official WotC books that might allow you to use a different cantrip with the Reaper Ability?

Answer 1

There's no such feature yet

Hard to prove a negative, but I don't think to date there are any features that allow you to cast other school's spells as necromancy spells.

I also don't see what your issue is — at least two of the three, Chill Touch and Toll of the Dead are really solid. Chill stops regeneration and Toll is the second best of all damage dealing cantrips after Eldritch Blast in the entire game, beating even firebolt.

Answer 2

I think the problem with your question is the premise. The school of magic is not some arbitrary characteristic slapped on a spell. School of magic determines what primarily the spell does and how. Therefore the necromancy spell is not necromancy because of anything other than its central behavior. So any feat or other effect that would switch school, would also have to fundamentally rewrite the spell. That's extremely unlikely to exist.

What could happen is that you can functionally recreate some other cantrip within framework of necromancy school. While that would require you to go through all the hoops required to actually come up with new spell, that's certainly possible. Then again maybe it's just better to create brand new one?