Fairly easy trophy to unlock, its earned by completing the Ace Hardlight challenge in the Dreadzone Battledome without taking damage. I used The Arbiter (Lv. 9) when I played. Simply circle around him in one direction the entire battle. At the start he'll attempt to shoot you with his blaster and throw pulse grenades, just strafe-jump over the blaster shots and pulse waves while firing rockets. After 4 or 5 hits he should use his healing shield. Use this time to gather ammo from crates that will start popping up. Next, Ace will spawn a bunch of hologram decoys around him, just shoot all of them to keep them from firing at you and then continue attacking Ace. After a bit he will start launching an arrow with a trailing energy stream that follows you, but it won't be a problem if you keep strafing in one direction. From this point on he will use the same attack patterns, besides adding a couple pulse grenades and decreasing the time he is vulnerable. Just keep strafing around him and firing rockets while dodging his attacks. If you need ammo, either collect it from the crates on the edge of the battlefield or use the charge boots to pick up ammo dropped by the holograms.