The Episode 11: Halls of Power Part I Add-on for DC Universe Online has 7 achievements.
Defeat 450 Dregg Warriors, Dregg Berserkers, Dregg Seers, or Dregg Huskarls
Complete the Intergang Crime Wave operation by defeating Bruno Mannheim and Chang Tzu at the same time, ensuring that neither have a chance to escape
During the Artifacts from the Past operation, defeat the second subboss at least once for each type of ancient weapon he wields
Defeat the final boss in the League Hall: Security Breach alert after recharging the Nullifier at least 12 times
Complete the League Hall: Lockdown raid without your entire team getting knocked out, and while allowing the intruders to create exactly three parts of the makeshift teleporter
Defeat 20 Dregg Wardens in the Necropolis: Relics of Urgrund raid
Collect all 9 Artifacts of Urgrund Replica Base Items