Calculated Retribution

You surround yourself with a dampening magical field and collect the energy of a foe's attack to use against them. When you take damage from a weapon attack, you can end the spell to halve the attack's damage against you, gaining a retribution charge that lasts until the end of your next turn. By expending the retribution charge when you hit with a melee attack, you deal an additional 2d10 force damage.