Counter of Thorns

You create thorns around you, stabbing an attacker. The attacker takes 4d8 piercing damage and suffers a penalty equal to the damage dealt divided by 2 (Example: 8 damage equals -4 penalty, or say 25 damage equals a -13 penalty).

When you cast this at a spell slot higher than 2nd, for every spell slot above 2nd level adds 1d8 piercing damage.