Has anyone ever bet the goddess ring? your opponent is doomkaiser and the prize is a soulbooster. But doomkaiser dies from getting zero mp instead of hp. Well, the colosseum enemies only have four attacks to use. Doom kaiser has attack, plague, draconic furror and dancing flame. Here is the way to be invincible to these attacks while doomkaiser slowly will perish.

character-Arc (his default evade is 28)
right hand: doombringer (gives 10 evade, drains lost mp)
left hand: red essence or blue essence (gives evasion and nulifies dancing flames damage)
head: serpent mask (absorbs poison damage)
body: misty coat (40% evasion bonus!)
relic: elven beads
relic: elven beads

With this equipment. Doomkaiser cannot lay a physical finger on you, plague heals you, dancing flame heals you, draconic furror is also blocked by evasion.

Though this a strategy that ensures victory, it would take some time to do so, but not that long, time flies by faster if Arc has learned the expensive spells (like meteor, nuke, meteo, radiance, etc), also rasp will do a heavy amount depending on level and stats.

Also for a note of danger, if arc has learned teleport, that just might screw you over.