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

[Gruntler]

Legit question: As a healer In Delub Reginae normal, the second of two debuffs that causes a super fast Doom.

Is there anything I can do as a healer, to prevent their death? Esuna or Heal to full heath?

Nope. In DR, if you fail two mechanics, you die. The avoidance is *not to fail twice in a that timespan.* One failure is fine though, you'll survive it.