How do you play arenas?

[Ziiv]

There are 3 or 4 “arenas” on my co op list that do not have any prerequisites. So I imagine I should be able to play them, but I can’t figure out how. How do you play these maps?

[Aurein]

Arenas are unlocked after hitting 50 and doing the contract quests for Defiant Few (its a long questline). After each one, a door pops up in the world to use for it. If it exists in matchmaking select before then, it might be a bug.

[Ziiv]

Oh ok. Thank you.