Contaminated Power (Contaminated)

When you cast this spell, you gain one level of contamination. You draw unrestrained arcane magic from the delerium shard you hold in your hand. Until the spell ends, you gain the following benefits:

-When you cast a spell that deals acid, fire, cold, lightning, or poison damage, you can change the damage type to force, necrotic, psychic, or radiant damage.

-Once per turn when you deal damage with a spell, you can deal an extra 1d12 necrotic damage for each contamination level you have gained to one target of that spell.

-When you cast a spell that forces a creature to make a saving throw to resists its effects, you can choose to gain one level of contamination. If you do, one target of the spell has disadvantage on its first saving throw made against that spell.

This spell can't be dispelled by dispel magic.

Discovering the Spell: A character who can cast 8th level spells, knows every other contaminated spell, and has cast each of them at least once can research contaminated power.

 * Credit to Monty Martin and Kelly McLaughlin via Dungeons of Drakkenheim