What 5* to upgrade

So I don' know what 5* to upgrade because I need to chose one of them WS but I have 4* Blade or 5* Iron Fist and I have no good mystic.

Comments

WS only when you have killmonger too then he gets really good

If you got a Killmonger man you will love him.

I hope I get Killmonger because I have Sabre.