Blood Armor

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 and it must have taken at least 1 point of damage from your attack; 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.