Gladiator Diemos
The pinacle of the Colosseum Bosses, Gladiator Diemos requires you to complete the Colosseum (as in win and get a ring) ten times before you can gain access. You must also complete a minor quest, described in Diemos Flagging. He drops the Gladiator Diemos Token that you give to the Master Arbitrator in return for the Gladiator Diemos Statue, the title "Immortal Champion," and a new token that can either be given back to the Master Arbitrator for a full level worth of experience or if you give the new token to Fiun Rehlyun in Fiun Outpost for a Blank Augmentation Gem.
Note: He continuously spawns platinum golems and spawns several other golems, called Guardian of Deimos which are very resistant and difficult to kill. Diemos has extremely high Health and it takes a while to kill him with a small group which due to restrictions on entry is all you'll probably have.
You give Master Arbitrator Gladiator Diemos Token.
Master Arbitrator tells you, "I see that you have proved you skill against the Champion, Gladiator Diemos. Well done indeed. I hereby grant you the title, Immortal Champion."
Master Arbitrator tells you, "In addition to your new title and this useful hook caster, I'll also give you a token that you can trade back to me for a great deal of practical knowledge, or you can trade it in to Fiun Rehlyun at the Fiun settlement in the Halaetan Isles for a blank Augmentation gem. A difficult decision, I know."
Master Arbitrator gives you Gladiator Diemos Statue.