Mid. Use stifling dagger to aid in last hitting creeps as it has a low cost and cooldown. Once you hit level 4, periodically harass the enemy mid with stifling daggers. Abandon mid as soon as you hit level 6 and start attacking heroes in other lanes with stifling dagger and phantom strike. Activating Blur makes you completely untargetable, not just invisible, for as long as you stay out of melee range of any enemies or enemy buildings. Activate blademail when taking fights.