Nautilus's ult can be cast onto Master Yi using nautilus's mana and setting his ultimate on cool down. Once the indicator is on Master Yi, Master Yi can use his Q and isn't knocked up. Once Master Yi is out of his Q he still has the target indicator from Nautilus's ultimate but is never knocked up.
http://www.twitch.tv/scg_gsu/v/16988775 is the video link and its 01:32:50 into the video
This is completely intended.
If a targeted ability hits Yi while Yi is still in the animation for Alpha Strike, the ability will not cause an effect.
This also applies to Fizz's Playful/Trickster (e) and Vladamir's Sanguine Pool (W)
He becomes invulnerable and untargetable during his Alpha Strike. (Much like Zhonya's as well.)
Pretty sure that's intended. Yi can avoid a LOT of spell effects (even targeted ultra, e.g. Caitlyn's ult, Veigar's ult, Karthus' ult, I think Fizz's ult, maybe even Vi's) by going untargetable just before the damage is dealt. Like that other poster said, Fizz and Vlad (and Shaco when he uses his ult) can do the same thing, as can anyone who buys Zhonya's or who is affected by Kayle's or Bard's ult.
