Early armguard means you are stacking ap and armor. Hextech and Visage secure you good hp/ap, all the cdr you will need, hp regen, and the active of hextech will give us AMAZING map awareness. Moonfire Spellblade is just beast and will make you tankier/harder to lock down/give you some ap. I dont have to sell gauntlet to you. Liandry's synergizes perfectly with all your slows from this build and will allow you to be tanky as hell while dealing a lot of damage. Randuins will make you nigh unkillable once you get it for late game and will allow you to peel for steve and I amazingly well stacked with gauntlet. The last two items are just for fun and only if you are dominating and feel like swapping them in - gunblade is a way better option for skarn than blade of the ruined king. My thoughts behind this build are itemizing to give you zone control/peel, tankiness (hp and cdr so your shield is up more), vision for ganks, very solid damage that works WITH your slows, be very difficult to lock down/give you engage AND disengage. I know it is tempting to get attack speed/life steal, but unless you are just going to be a damage dealer, I think it is a false economy and tankiness/cdr/ap will make you a better all around tanky damage dealer.