For those of you who don't know, there's a major change for the Celerity rune on the PBE right now.
[Changed Effect] "Movement speed bonuses are 10% more effective on you."
The reason for the change stated is that they want to "free up ADC choices." I think this is an entirely wrong way to go about this. The reason most ADC's are going Absolute Focus instead of Celerity or Transcendence is that they want damage, not movement speed or CDR. Removing the (+6% bonus movement speed) bonus AD and offering more movement speed won't incentivize the ADC's who are taking Absolute Focus to take Celerity instead. If anything, it will just drive even more ADC's to take Absolute Focus because it'll be the only rune of the three to offer damage.
I would also like to point out that junglers like Nocturne and Xin Zhao, two of the more popular Worlds 2018 junglers, will be severely and unreasonably nerfed by this change. Nocturne's kit currently gains him around 34 AD for two seconds with the current Celerity. Xin Zhao gains around 12 AD for 3 seconds with the current Celerity + Phase Rush. Now, this may not seem like much but for auto-attackers like these two, losing that AD will have a huge impact on their win condition. To illustrate, on patch 8.11, Xin Zhao lost a whopping 4% win rate (54% to 50%) after his AD was nerfed by just .3 AD per level (-6 AD at level 18). Imagine what losing 12 AD would do to him, let alone to Nocturne who's losing 34 AD in his combo. Yes, those two are strong right now (both hover around the 51-52% win rate), but this Celerity change will destroy them to the point of non-viability.
Please Riot, please. Don't go through with the Celerity changes. It's not going to make ADC's choose Celerity, it's just going to hurt a lot of junglers that rely on the bonus AD.