Caustic Blood

Your blood becomes caustic when exposed to the air.
When you take piercing or slashing damage, you can use
your reaction to select up to three creatures within 30
feet of you. Each target takes 1d10 acid damage unless it
makes a successful Dexterity saving throw.
At Higher Levels.When you cast this spell using a
spell slot of 3rd level or higher, the number of targets
increases by one for each slot level above 2nd, to a
maximum of six targets.