Curse of Vengeance — ruling 1

Curse of Vengeance's first triggered ability resolves before the spell that caused it to trigger. The ability will resolve even if that spell is countered.

Curse of Vengeance — ruling 2

If you and the enchanted player both reach 0 or less life at the same time, you'll lose the game before Curse of Vengeance's second triggered ability gives you more life.

Curse of Vengeance : règles, fonctionnement et interactions (MTG)

Curse of Vengeance is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Enchant player Whenever enchanted player casts a spell, put a spite counter on this Aura. When enchanted player loses the game, you gain X life and draw X cards, where X is the number of spite counters on this Aura.

How it works : Curse of Vengeance

Original English text — Wizards of the Coast / Scryfall

#1November 8, 2016· Wizards of the Coast
Curse of Vengeance's first triggered ability resolves before the spell that caused it to trigger. The ability will resolve even if that spell is countered.
No other card is named in this ruling.
#2November 8, 2016· Wizards of the Coast
If you and the enchanted player both reach 0 or less life at the same time, you'll lose the game before Curse of Vengeance's second triggered ability gives you more life.
No other card is named in this ruling.