Potion of Shielding
There are different variants of this potion, when you drink one of these potions you are protected against a single damage type. You gain resistance to that type of damage and a shielding aura surrounds your body. Whenever a creature within 5ft. of you hits you with a melee attack, the shield erupts, dealing 2d8 damage of that type to the attacker. These effects last for 10 minutes.