Blood Armor

3rd-level necromancy (blood)

Casting Time: 1 bonus action
Range: Self
Components: V, S (you must have just struck a foe with a melee weapon)
Duration: 1 hour

When you strike a foe with a melee weapon attack, you can immediately cast blood armor as a bonus action. The foe you struck must contain blood; if the target doesn’t bleed, the spell ends without effect. The blood flowing from your foe magically increases in volume and forms a suit of armor around you, granting you an Armor Class of 18 + your Dexterity modifier for the spell’s duration. This armor has no Strength requirement, doesn’t hinder spellcasting, and doesn’t incur disadvantage on Dexterity (Stealth) checks.

If the creature you struck was a celestial, blood armor also grants you advantage on Charisma saving throws for the duration of the spell.