Climactic Strike

The next time you hit a creature with a melee weapon attack during the spell's duration, your weapon bursts with dramatic tension, and the attack deals an extra 1d6 thunder damage. Alternatively, you can choose to hold the dramatic energy by not attacking with the weapon and letting the tension build. For each turn you spend holding and building the energy, the extra thunder damage increases by 1d6, to a maximum of 4d6.