The Devil You Know

To get this quest flag and be eligible for Tower of Despair raid, you have to beat 4 Devil Battlefield quests.
 * A New Invasion
 * Bastion of Power
 * Genesis Point
 * Sins of Attrition

The Weapons Shipment and Wrath of the Flame is not required.

Also, Boots of Archoning is not required to get into the raid.