Dark Harvest is an excellent rune choice for securing easy kills thanks to your ability to easily proc it with the use of your high burst and passive dot.
WhyTaste of Blood
Taste of Blood allows you to trade early and often in lane, making good use of your high base damage.
WhyEyeball Collection
Eyeball Collection Stacks are relatively easy to acquire in teamfights/skirmishes where you're able to tag multiple people with your [R] and passive explosion.
WhyRavenous Hunter
Ravenous Hunter's spell vamp synergizes incredibly well with you high base damage and passive DoT allows you to play aggressively while staying healthy.
WhyManaflow Band
Manaflow Band acts as your primary means of mana regeneration (paired with your support item).
WhyScorch
Scorch doubles down on your early game damage dominance, setting you up for early kills and snowballing a lead.