Locked out of the Meta: Lifestealer

I would give him a new ability. Rather than Rage He would get:

Crazed Shamble:

Lifestealer channels his flesh-lust into one attack. He gains the "Crazed Shamble" buff for 10 seconds which grants him movement speed. If affected by CS, upon contact with an enemy ( a right click attack ) he tears off a chunk of flesh and consumes it giving him a portion of health, armor, and attack speed. He loses the movement speed upon attack.

Channel Duration : 3 / 2.25 / 1.75 / 1 second(s)
Movement Speed Bonus : 10%
Damage to Enemy : 33% of current HP.
Health Back : 12% of Max HP
Armor : 3 / 4 / 5 / 6
Attack Speed Bonus : 15%
Cooldown : 10
Manacost : 100

I think that scales well but gives him more survivability. It gives him tank killing power that weakens the lower an enemy is. It is percentage based so Items like Hand of Midas , Phase Boots, and Maelstrom (His Cores) would increase it's power.