Champions

[Ashe]

Riven passive procs, Renekton's W, Pantheon's E passive, WK Q, Udyr bear/tiger harass, GP passive proc (15% dmg reduction basically negates his E too). Yeah it'll hurt all of them. It's going to be THE boots to get in top lane. Less variation than before really...

I don't think its going to single handedly remove Riven from contention. Not really going to address Renekton's W nor Wukong's Q because that entirely comes down to seeing it in action and knowing that - unless this is the end of the world - they will just adjust it if there's a problem. Udyr has already been addressed, but as far as it just shutting down Pantheon and GP, I disagree. I think the dmg you might be losing from that minor amount is more than mitigated by lack of Merc Treads (Tenacity for all of the above character's stuns that ENABLE them to autoattack like that) that will also hurt them later in the course of team fights.

Really, I don't think Ninja Tabi becomes "The new default purchase" so much as it gives Merc Treads a possible contender to pick between (with the very occasional Move3 purchase). I would definitely not call that "less variation" because Merc Treads were more or less THE boots to get, even after they added new Tenacity items and then BUFFED THEM to try to deal with that. Ultimately, both will be mitigating a bit of dmg from their chosen direction.

Also, looking at it from the angle of "it completely negate's Plank's E" might be slightly skewed. Plank's E will still likely let him outrun whatever freakin' boots you bought so he can get more free hits in and reset his passive, still netting him free dmg. In that scenario, I take the side that "Plank's E essentially negates the dmg loss from Ninja Tabi".

And just to clear it up... GP's passive is not "an auto attack" nor is every AD caster ability that hits for physical instead of magic. Just because a move scales on AD rather than AP, even if it procs on-hits, doesn't immediately code it as an auto attack.