Lane dominance kill pressure and poke.
Burst damage and target access
Damaging a lot health champion inflicts adaptive damage and harvests a soul form the victim.
Recover health when you damage an enemy champion.
Collect eyeballs for champion and ward takedowns. Gain permanent AD or AP, Adaptive for each eyeball plus bonus upon collection completion.
Heal for a percentage of damage dealt with your abilities. Increases with each unique takedown.
Empowered abilities and resource manipulation
Hitting enemy champions with a spell grants maximum mana.
After reaching 250 mana, Manaflow Band restores 1% of your missing mana every 5 seconds.
While above 70% health, gain up to +40 Ability Power or +28 Attack Damage (based on level), Adaptive.
+5 AD or 9 AP
Dark Harvest is an excellent keystone on Heimerdinger for ensure kills thats to your ability to easily proc it with [Q] turret damage.
Taste of Blood offers excellent lane sustain with your ability to easily deal damage from range with [W].
Eyeball Collection's snowballing nature is great for taking advantage of small leads from kills and assists.
Ravenous Hunter offers you excellent sustained healing with your ability to constantly deal damage with [Q] turrets.
Manaflow Band is huge for ensuring your ability to sustain your poke and pressure until you're able to get your first mana item.
Absolute Focus' health threshold is relatively easy to sustain with your long range and healing from Taste of Blood and Ravenous Hunter.