Runic Bear Overpower

I really wonder why runic bear are so overpower Phantom Assasins cant even win in 1on1 i was like WTF when my lil bro choose Shapeshifter lvl 200+ his atck already is 71k crit and 40k+ like compare with my assasin 54k crit with just 25k hp, is this game lack of balancing of characters? please answer i cant even solo Diablo with no pots but the runicbear can, + phantom assasins ``Assasinate last skill cannot be use on PVP, `` i hope when i get limit breaks it would be fair to all charcaters