Plague Reaver — ruling 1

If the chosen opponent leaves the game after the activated ability resolves but before the delayed triggered ability returns Plague Reaver to the battlefield, Plague Reaver stays in the graveyard.

Plague Reaver — ruling 2

If Plague Reaver is put onto the battlefield under the control of someone other than its owner, and that player leaves the game, Plague Reaver is exiled.

Plague Reaver : règles, fonctionnement et interactions (MTG)

Plague Reaver 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

At the beginning of your end step, sacrifice each other creature you control. Discard two cards, Sacrifice this creature: Choose target opponent. Return this creature to the battlefield under that player's control at the beginning of their next upkeep.

How it works : Plague Reaver

Original English text — Wizards of the Coast / Scryfall

#1November 10, 2020· Wizards of the Coast
If the chosen opponent leaves the game after the activated ability resolves but before the delayed triggered ability returns Plague Reaver to the battlefield, Plague Reaver stays in the graveyard.
No other card is named in this ruling.
#2November 10, 2020· Wizards of the Coast
If Plague Reaver is put onto the battlefield under the control of someone other than its owner, and that player leaves the game, Plague Reaver is exiled.
No other card is named in this ruling.