Have you considered removing the tumble cooldown and just giving her power elsewhere? It is the most frustrating part of her kit.
Definitely. It's a balancing act of trade-offs, with the goal being to reduce Vayne's playing against frustration while leaving the playing-as-Vayne experience as fun as possible. The introduction of the mechanic earlier this year increased Vayne's play-rate pretty considerably, so looking to see if it can exist with slightly reduced power. Would definitely consider removing it completely (or think of some other mechanics change) if Vayne continues to be an issue post 9.10