Unstable War Beast
From Destinypedia, the Destiny wiki
Unstable War Beasts are distinguishable by their silver-colored armour. They will usually spawn into a Battleground if players fail to throw a Unstable Power Charge, dropped by an Unstable Incendior, onto a Power Cell that is charging the targeting arrays of the Imperial Cabal.
They are summoned into the arena through Ripper Pods and will roam around the various Power Cells in order to guard them. Unlike most War Beasts, the Unstable variant is passive in gameplay and will only attack if players get too close to it. They are highly durable and evasive, and will compensate their lack of ranged attack through close combat. They will relentlessly attack players with their teeth and claws.
List of appearances