Double Damage rune:

The Double Damage rune is a power-up in Dota 2 that temporarily greatly increases a hero’s physical attack damage. It is one of the standard rune types that can spawn on the map and is often contested because it can quickly swing fights, secure kills, or speed up objective damage such as towers and Roshan.

Players commonly pick it up before looking for a fight or when they want to threaten the enemy with stronger right-click damage. It is especially valuable on heroes whose damage comes mainly from basic attacks.

Related: Bounty rune, Rune, Roshan, Last Hit