Crimson Poison

You sacrifice up to 5 hit points (included in the material components) and invest them into an ichorous crimson poison coating that coats a weapon you are holding. The next three times you deal damage with that weapon, it deals acid damage equal to the hit points invested. After dealing damage with the weapon three times, the spell ends. If the spell ends before dealing damage for a 3rd time, the blood dries, becoming non magical and harmless.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, you can invest up to 1 additional hit point in the casting for each slot level above 1st, up to a maximum of 10 hit points at 6th level.