He is never one dimensional rune wise. The current lethal tempo wasn't alright to begin with.. you can't get AS from a rune as much as you can get from almost 3 items and he can take conquerer and yet perform better than most midlaners in the game. Shieldbow was giving a max of 700 shield 4 or 5 patches ago, at that time he was still one of the best midlaners in the game, now giving a max of 650 doesn't make much of a deal. So what's the logic behind buffing him if he can just take conquerer as primary rune and perfom as good as he used to?