History of Ogre Ascendant

Overview

The Ogre Ascendant is an Ultra-ranked Taken Ogre. The standard version belongs to Savathûn's Brood. A Dire variant belongs to the Dire Taken and appears in The Nether, where the Dire version adds Rapid Movement and Taken Burn (Solar) to its standard abilities.

Trenchway secret

In the Trenchway of the Dreadnaught, the Ogre is summoned by the Burning Pillars. Light the first pillar across the semicircle platform past the large crossing, then use the platforms your Ghost reveals to reach the far side. Light the other two pillars to summon the Ogre. Defeating it reveals a Secret Chest. The Dredging Up Secrets II triumph also targets a chest hidden deep in the Trenchway.

Destinypedia describes a different trigger, a trio of torches near the entrance to Oryx's arena in Regicide, which only sometimes spawn.