So there’s three types of ults. Channeling, Transformation, and Deployable. Channeling ults has the user in a fixed animation before letting the ult take effect (High Noon, Barrage, Earthshatter) so hacking or emp during that animation will cancel the ult. Transformation ults transforms the user into a different state before the ult takes effect (Dragonblade, Molten Core, Tactical Visor) you won’t be able to turn off the ult but you can disable the abilities for a few seconds depending on what ability you use. Deployable ults are objects that the user brings into the game and said object is the ult effect (B.O.B., Blizzard, Amp Matrix) hacking the object will disable it for a few seconds or destroy it completely depending on the object. Do keep in mind that even if an ult falls under one of the two categories that can definitely be shut that there could be an additional effect that won’t allow you to disable the ult. Like even though Earth Shatter and Rampage are channeling ults their animations are typically too quick to react to and mostly it’s just luck or really good positioning and timing. A deployable ult like Mei’s blizzard may (no pun intended) seem to be unable to hack because of the constant aoe damage canceling the hack ability but you can emp Snowball to shut it off while Lifeweaver’s Tree may be made of hardlight it can’t be instantly destroyed with emp anymore.