Doom Effect

I just got my quest done to pop Ig-Alima I found out Zeid II Stun most the death strike from Ig-Alima 90% of the time anyways.

What I don't understand once you get timer for DOOM and use holy water 3x time it still kills you off?

Trust I used

Kupipi + Ferreous Coffin (need to try Trust: Ingrid II Trust: Nashmeira II)
Zeid II

any death equipment one can use?

Holy water has only 33% base chance to remove doom.

You can use several items to increase this chance:
Purity Ring (+7%)
Blenmot's Ring (+5%)
Blenmot's Ring +1 (+10%)
Nicander's Necklace (+30%)

If you make a gearset for Holy Water, may wanna make one for Cursna Received too, unless you spam Holy Waters

Eshmun's Ring +20%
Gishdubar Sash +10%
Nicander's Necklace +20%
Purity Ring +7%

Or just make a combined set.
Nicander's Necklace +20% Cursna, +30% Water
Purity Ring +7% Cursna, +7% Water
Blenmot's Ring +1 +10% Water, or Eshmun's Ring +20% Cursna
Gishdubar Sash +10% Cursna

I was thinking Shadow Ring would be there as well?

Protects against death is instant death attacks.
Endeath from Wrathare, maybe Ngai Marine Mayhem?

Correct, resist death doesn't help against doom. You can sometimes resist the doom landing with magic evasion & dark resistance in which case you never even get a countdown, but if doom lands and the timer runs out then you will 100% die. There's no way to prevent that besides removing the doom via Cursna & Holy Waters before the timer runs out.