The colosseum there features two modes, “United Combat and Combat Ordeal”.
Whoever has the most when the timer hits zero wins.
The Royal Colosseum in Leyndeel, meanwhile, is all about duels.

No respawns, just a good ol' 1v1 showdown.
The Caelid Colosseum includes all the modes above, but lets you summon Spirit Ashes.
Convenience is swell but player-enforced customs are special.

The Colosseum update also added some new hairstyles, along with various balance adjustments.