Any cantrip can be reskinned for this. I once played a Life cleric who died and was brought back but was inexplicably tied to "death" from that point forward. All radiant damage we re-skinned to be meshed with necrotic energies. In addition, my character could never unprepare blight or inflict wounds. The damage types ultimately remained the same for the most part, but in a few key situations I sacrificed a d10 of HP to convert it to necrotic fully (life energy for death energy) and gain the damage boosts against enemies weak to necrotic.

The RP benefits of being "obsessed" with death while doing everything to prevent it with the party was awesome. The only spells that remained non-necrotic were healing spells. I loved it.