Cnidari-Veil

You conjure up a shroud of spectral jellyfish that float around you in a 5-foot radius sphere. Any time you are hit with a melee attack, the jellyfish lash out at the attacker. The attacking creature takes 2d4 Lightning damage and must make a Constitution saving throw. On a failed save, they cannot take reactions and are poisoned until the end of their next turn. On a success, they are not poisoned, but cannot take reactions until the end of their next turn. 

At Higher Levels: When you cast this spell using a slot of 3rd level or higher, the lightning damage increases by 2d4 for each spell slot level above 2nd.