Illusion rune:

The Illusion rune is a power rune that creates one or more temporary copies of the hero who picks it up. These illusions can be used to scout, push lanes, farm, or confuse enemies, but they deal less damage and take more damage than the real hero.

Because the rune can be claimed from the river, it is often contested by both teams and can affect map control around rune spawns.

Related: Power rune, Rune, Vision