From Outwar Wiki
Talk to Coagulated Knight - Room 249 - In the first room when entering Stizzy waterway keep , from the mysterious portal .
He'll ask you to bring him Zertans Bracer.
Go kill Zertan, since it's a spawn mob you'll have to kill all the enigmatic terrors in his room to spawn him and kill him even several times since the bracer doesn't drop each time (hard mob !!) by bringing the bracer you'll receive his Helmet (painfully low drop).
Reward is a Coagulated Helmet and 15,000 experience