It definitely is overtuned. Id like to see what it would perform like with major timidity over minor.
I'd be careful with that, that isn't something you can just always compensate with skill. Running around to farm ult between engagements sounds quite tedious. Maybe the ult drain can rather be attached as "ammo" to the status ticks or so (with a 0.1s timer lock per status type so that AoE procs don't punish the user)...so moderate users get moderate penalties, etc. That would probably result in a even steeper effective cost on Cringing Shock spam without much of the hassle while stuck in combat.
The Mythic should remain fun and usable on non-burst builds.