Vermilion Mantle

You wrap yourself in a living mantle of blood magic. For the duration, you gain the following benefits:

Your AC increases by 1.
You have resistance to Necrotic damage.
When a creature within 5 feet hits you with a melee attack, it takes 1d8 Necrotic damage.
Once per turn when you deal Necrotic damage to a creature, you gain temporary hit points equal to your spellcasting ability modifier.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the retaliatory damage increases by 1d8 for every two slot levels above 4th.