How to get the white ring to unlock a path in final quest of this months Side quest?

I have completed all the solo objectives . Yet i dont have the white ring.From where it is available? Is it a bug? Do help me.

Comments

Check your objective list on bottom right where it shows digit 1 . The description is mentioned there.

Edit - it's in arena

Arena!

Arena unfortunately

Thank you guys! Unfortunately i forgot about the arena. Thanks all of you guys!