My answer to that? Drop a Bishop on the mammets, maybe even hit em with Flamethrower, and the healer? Blank out of Asylum, stun, then "1-2-3-4, you-don't-exist-anymore." And while that burst might still be potent enough to take down my intended target, the damage wouldn't be at current endgame potency. It never was. An ilvl sync would be in place still. Keep in mind, I took down many a healer with that burst back when healers were so powerful then. Only reason I can't do that so easily now is that burst literally doesn't exist, and healing potencies sit well above the most potent attacks I have.
Again, I encourage you to look at the job guides. It's all there. MCH has no oGCDs besides the nerfed BTE, Blank, and Leg Graze. . . Guess what Benison, Regen, and Benediction are?