Watcher of Crota
From Destinypedia, the Destiny wiki
Like with normal Wizards, Watchers will fly around the arena and periodically send barrages of Arc projectiles at players, and when they get too close they will conjure a cloud of poison which slows them down and damages them continually. Watchers have the additional ability of being able to summon Vestiges on the ground, which will damage players who step on them and remain even after the Watcher who created them has been killed.
List of appearances