Which 6* champion to rank up?

I have multiple 6* Champions, which does not exist as 7*. Guide me for crucible quest.

Comments

There are a few Crucible fights where buff immunity is very useful. Not to mention, RG hits hard

Kingpin all day long!! He's the best skill champ in the game

Kingpin all day long!! He's the best skill champ in the game

Laughs in Kate Bishop