This is a build I just tried out for a few games and it works wonders! Last game I played I shot The Butcher 5 times in a row and prevented him from blowing his Furnace Blast up in my face, it was awesome.

Level 16 you may want to take the stun Q, but since the cooldown is so short, I opted to go with the higher damage.

The second build allows you to continually have your heroic available. Only good on smaller maps that are team fight oriented such as Battlefield of Eternity, Dragon Shire, and Infernal Shrines.