This build is for a straight attack speed and damage. You will have to be a little more careful when attacking towers and enemies. Although rampage will be slightly squishy he will deal out damage very quickly. Just make sure to pop your ultimate before engaging in uneven team fights.
I like to start out with the beast master key then move to attack speed. Helps clear out the jungle quickly so you can get feed asap.
Late game you will be able to melt the enemy team and towers.