Talk:Ability effects/@comment-10022923-20130601163117/@comment-3116092-20140131170822

all physical damage done from sources that can proc on-hit effects (couple exceptions aside). onhit effects themselves cannot proc other onhit effects (nashors won't proc wits which in turn proc nashors again) and thus they, themselves cannot proc lifesteal. The 5% damage from bork is an on-hit effect and does NOT proc lifesteal. on-hit effects never proc lifesteal.

The spellblade passive on Sheen and the like is NOT an on-hit effect, despite the page reffering to them as such, they are auto attack modifiers, similar to nasus siphoning strike and Blitzcrank's knockup. They proc lifesteal, can affect turrets (which is ofcourse immune to on-hit effects), can get reflected by thornmail passive (which does NOT reflect onhit effects, again likely due to its a onhit/whenhit effect which isn't allowed to proc other onhit effects), and the modified damage is usually not subject to critical strike chance.

Spellblade is not an exception to the onhit--lifesteal rule, it is actually categorically different from on-hit effects. Muramana is a trigger effect, meaning its both an on-hit effect and on ability effect, neither of which proc lifesteal (but possibly spell vamp I need to confirm).