TL:DR: Quaking is poorly designed and needs to be dropped as an affix.
I’ve tried to think about how that would play out. Quaking has a 20 second cd and probably has something like a 90% chance to proc when the cd is up. Sometimes you get a brief respite when it skips one cast, but this can actually be a downside to the mechanic. With a timer mod you find yourself waiting to eat until quaking, but if it skips you’ve just been waiting for nothing.
To that point though, players who don’t have a timer mod can constantly get caught out by it, which is diabolical. For example, tank pulls and quaking starts; now casters can’t precast, the group starts the encounter at a 20% health deficit and the healer is immediately on the back foot. Without a timer you can’t play around the affix, it just happens, and far too many times that prevents me from healing someone who desperately needs it, taking all control out of my hands. Being helpless in a game is a rotten feeling.
My biggest concern with making it cease out of combat is that many boss abilities are probably scheduled to occur on a timer that would line up directly with quaking. Overlap would be inevitable. If the timer was randomized you’d probably never get a drink off and getting food buffs after a death would probably be even more infuriating than it is now.
Personally I think it needs to be dropped as an affix. Preferably from a great distance, on top the head of the ding-dong who invented it.
Last week, Siege had a 3% success rate for the top 1000 keys. ML was 5%. All thanks to how Bolstering make trash mechanics, that do upwards of 70% health per hit, and ramped them up to one-shots.
This week the same dungeons’ success rates are trending downward, which I expect to drop dramatically over the weekend where more keys are run, precisely for the same reasons: mobs that have abilities that hit for massive percentage of a players health, such as Rock Lance, or Merciless Assault often line up with Bursting or Quaking, or both and simply dunk players in the graveyard faster than they can blink.
A 3% success rate, among the TOP 1000 runs, not the lower brackets of lesser geared, or prepared players, is just not right, in my opinion. It’s fine for solo activities like the mage tower. Where a player can adapt and progress until they complete it. For group content, where the party members are constantly in flux, where blame is far too easy to assign and resentment too easy to foster, is deadly to the community. Challenge is good, but when it leads to 97% failure rates, especially when it comes in the form of uncounterable, unavoidable affixes, it’s demoralizing and detrimental to the health of mythic plus and game as a whole.
I don’t want a free ride, but I don’t want to be tied to the bumper and dragged across the instance on my face.