I just had this idea about building Life Steal items for N'aix, the Life Stealer. I know that his Feast is more than enough for life stealing, and I usually don't go building life steal items, but rather consider about improving his DPS by building more damage and IAS items.
However, I noticed this about LifeStealer's abilities. First of all, Feast is not an orb effect. That means, it should stack with any other life steal item. And since he is melee, we can use Vladmir's Offering as a life steal item too. That means, if we could build Valdmir's, Helm of Dominator and upgrade his Feast skill, all should stack. What if we enhance Helm to Satanic? Vladmir's offers 17% Life Steal, Satanic 25% => 42% Life Steal. With Satanic's Active, that would be 52% Life Steal!
And then again, Feast has its own way about calculating how the life steal happens (with regards to the enemy's current HP percentage), but with Level 4 Feast, it restores 7% of enemy's current HP per hit. That means with all those items, he would be unstoppable (well, he would be unstoppable only with feast as well).
(Please limit your discussion to the topic, Life Steal for Life Stealer. This is not a discussion about which item is best suited for Life Stealer)