Gladiator Diemos
From Drunkapedia
The Colosseum boss that requires you to complete the Colosseum (as in win and get a ring) ten times before you gain access. He drops a token that can be turned in for a spell casting statue, a token that can be turned in for xp or an augment gem, and also the title "Immortal Champion".
Note: He continuously spawns platinum golems and spawns several other golems called "Guardians of Deimos". He has extremely high HP and it takes a while to kill him with a small group which due to restrictions on entry is all you'll probably have.
