I build AD/HP with him. His AP scaling is pretty bad in general, plus his abilites are not too spammy. You get some AP through souls already to put a little damage on those abilities. He is ranged and his passive on-hit damage from Flay scales off AD/souls, so he can hit pretty hard with those AAs with some AD investment. I usually start Brutalizer->Black Cleaver then build Entropy or Frozen Mallet depending on how the game is trending. Slap a Hurricane on there for funsies.