Build lacks forthought and the core items are too expensive unless your in the low elo or lvl <30 range this is not that good. You make no use of increasing his attackspeed (other then trinity) untill very late game, and you also dont make use of his AP and the bonuses in the rune page. Also Skarner is not a crit character more like a offtank dps initiator so build him like that bro.