Sanguine Retaliation

2nd-Level Transmutation Spell (Sorcerer, Warlock, Wizard)

Casting Time: Reaction, which you take when creature that bleeds takes slashing or piercing damage
Range: 60 feet
Components: V, S
Duration: Instantaneous

When a creature that bleeds, and is in range of the spell, takes slashing or piercing damage you may use your

A Reaction is a special action taken in response to a trigger defined in the Reaction's description. You can take a Reaction on another creature's turn, and if you take it on your turn, you can do so even if you also take an action, a Bonus Action, or both. Once you take a Reaction, you can't take another one until the start of your next turn. The Opportunity Attack is a Reaction available to all creatures. See also Opportunity Attacks and Actions.

to instantaneously sharpen the spilt blood into needles and blades that strike the target. Make a spell attack roll against the target with advantage dealing 1d8 piercing or slashing damage per 5 hit points of blood spilt up to a maximum of 30 hit points/6 blood masses.

At Higher Levels: The hit point maximum increases by 15 and the blood mass maximum increases by 3 for each spell slot level above 2.

Source: Champion's Ascension