A glimmering sphere is directed to a target that has a continual spell effect on it. The spell energy is enhanced and surges into the target, consuming the remainder of the spell's energy. The target takes three rounds of damage from the spell effect instantly, normal saving throws apply (one roll), and the spell ends.

Example: A target being hit by Witch Bolt normally takes 1d12 damage per round. When Arcane Rush is used on the Witch Bolt, the target takes 3d12 damage immediately and the Witch Bolt spell ends.