Two-Step

You drive a creature forward with an aggressive rhythm impossible to stand still against.

Choose yourself or one willing creature you can see within range. Until the end of the target's next turn, its Speed increases by 15 feet, and its movement doesn't provoke Opportunity Attacks.

The first time during the spell's duration that the target moves at least 15 feet and then hits a creature with a melee attack on the same turn, the attack deals an additional 2d6 Thunder damage.

Using a Higher-Level Spell Slot. The additional damage increases by 1d6 for each spell slot level above 2.