He IS underpowered for sure. He needs QUITE a few tweaks. BUT if you just cant seem to take your hands off of him like I can't....
Build sheen first. You DO NOT need to build tank early on cause early he is strong and can hold his own. Take sheen and make it into a frozen gauntlet or trinity, followed by STERAKS. I am finding that mid game, this item is MANDATORY on this champ to do decent damage and survive until your last 3 items are completed. THESE will be your end game tank items that help you scale late game.
Ofcourse max W and then Q. E is last cause its damage sucks and youre only probably use it once per teamfight for the cc anyways.
This appears to be pretty solid so far, still experimenting, but tell me what seems to work for you guys in the comments below! ;)