Just throwing this out here as feedback to SE. The Vault's last boss as a healer is incredibly unkind. There is so much stuff going on during the fight its difficult to keep people alive at all.
If you (or your party) lag or miss a step, as a healer it pretty much means the party wipes. I've done several runs of this and nearly everytime atleast one party member died or it was an outright wipe.

If just one mechanic were removed or eased up it wouldnt be so chaotic. But as it stands now its a nightmare to heal through it. Every other healer I talk to says they either refuse to heal it (which is causing longer Queues for that dungeon specifically) or they dread the thought of healing it. So far I'm the latter, but Im quickly debating just leveling in the Aery until I pass this dungeon outright. In fact, if it werent for the fact that I want the WHM body piece from here for glamour purposes I would likely have ditched The Vault ages ago.