Unavoidable death mechanics should not be a thing in FFXIV :(

[MistakeNot]

My wife has earned herself quite the bragging rights over me but she should have been able to have even more bragging rights—but an unavoidable mechanic that targeted her killed her in The Orbonne Monastery. And there was absolutely nothing she could have done to avoid it

There are no unavoidable death mechanics in FFXIV.
Some mechanics are difficult to avoid, and some require you to know and prepare for them in advance, but none that are unavoidable.