Vayne's Tumble
At rank 5:
90-Caliber Net - slow, 10 second CD.
Valkyrie - DoT, 14 second CD
Arcane Shift - extra attack, 11 second CD.
Quickdraw - attack speed, 14 sec CD.
Relentless Pursuit - Lightslinger (double--shot), 14 sec CD.
Rocket Jump - damage, 14 sec CD.
Notice how all of these champions have a long cooldown on their dash/mobility, with a mostly negligible additional effect (except Graves/Lucian)
Tumble - 50% more damage, potential 6 second stealth, 2 sec CD.
WTF?
All of the other champions I listed are easy to abuse if they misuse their mobility spells. Since they have such long cooldowns, it is easy to punish them if they use it aggressively. They have to choose if they want to risk using it to get a kill, or save it for escape. Vayne is the exact opposite. She can use it EVERY 2 SECONDS, so she doesn't even have to think about saving it. To make matters worse, she gets 50% more attack damage (a lot), a SIX SECOND STEALTH with her ultimate, and best of all? She can use it again in another 2 seconds. WTF IS THIS?