OK. so how does 
actually work. If 
Q's, when he strikes, will his attack have sheen's passive, or will his next auto attack? Same thing with 
, if he Q's, will the stab get affected by sheen or will his next auto?
M Schumacher3 votesnasus q is an empowered auto so it applys with the q
anything that is an empowered auto (like gp Q) apply it.
FiniteHD1 votesHow does it work with GP? That seems odd, It's just a normal skill shot, like Ahri's charm.
Blue Collar Bear2 votesGangplank's Q acts as an empowered auto. If I'm not mistaken, he's the only champion to have a ranged empowered auto.
FiniteHD1 votesOh, that's pretty cool! So for example, if I use Rengar's Q (His Stab) Sheen's passive will be used on the follow up stab?
Blue Collar Bear1 votesExactly! Rengar's Q acts as an ability that immediately activates Sheen's ability. When it hits a target, the extra damage is applied.
What happens with Gangplank is an all-in-one where you use his Q and the Sheen proc is on the ability you use, which is why most Gangplanks almost always built Trinity or Gauntlet (and AP GP building Lich Bane).
BattleOoze1 votesOh, that's pretty cool! So for example, if I use Rengar's Q (His Stab) Sheen's passive will be used on the follow up stab?
The way sheen works is after using an ability, your next aa is empowered doing extra damage. Now if the champion has a skill that applies on hits such as GP's q or Rengar's q, it will apply it automatically. Get what I am saying? Ezreal's q isnt an aa BUT the spell applies on-hits. On-hits include red buff, phages passive, frozen mallet's passive and so on.
Darth Valer1 votesGP has no skillshots (except, perhaps, his R). HIs Q is a point-and-click spell which is considered as a melee autoattack and procs Sheen effects on hit (Sheen effects = 
).