I ran about 70 games and the win rate came out about 64% in legendary rank.
Due to the nature of the mid-range deck, the agro-deck must be blocked and won, and the control-deck must be scammed and pierced.
As you can see from the previous record, it's worth noting that except for the mechanical paladin that kicks off in the beginning and the cube warlock that kicks in 5 turns.
Mulligan has a common one mana cost minions and it's too basic to take Keleses.
If your opponent seems to be an agrodeck, take Tar Creeper. Especially against odd devil hunters, the glacial spirit is very good.