NOT INCLUDING ULTIMATES
Duelist: Jett's Dash - even after the nerf, it lets Jett disengage and avoid being traded out once per game. That's an insanely strong ability, and should never be underestimated.
Honorable Mentions: Raze nade, Neon's running, Reyna dismiss
Controller: Viper's Wall - this ability is the only smoke ability that covers a long stretch of area at once, and it's what makes Viper a must pick on Breeze and Icebox.
HM: Astra suck, Brim molly
Initiator: Kayo knife - this knife's information and suppression abilities are insanely powerful. It can single handedly stop a push for 7 seconds, provide critical info, and do so without any chance of being broken because it doesn't need line of sight like Fade's haunt and Sova's recon dart.
HM: Fade sieze, Kayo flash, Fade haunt, Skye flash, Sova recon dart
Sentinel: Chamber's Teleport - similar to the Jett dash but even more broken. Lets Chambers play in crazy off angles and take fights that would be suicide for any other agent.
HM: Chamber Headhunter, Sage wall
Feel free to leave your opinions below!!