Peacekeeper — ruling 1

When the ability resolves, you choose whether to sacrifice the creature or perform the other action. If you can’t perform the other action, then you must sacrifice the creature.

Peacekeeper — ruling 2

If the creature is no longer on the battlefield when the ability resolves, you may still perform the action if you want.

Peacekeeper — ruling 3

Peacekeeper’s ability doesn’t cause the combat phase or the declare attackers step to be skipped.

Peacekeeper : règles, fonctionnement et interactions (MTG)

Peacekeeper 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 upkeep, sacrifice this creature unless you pay . Creatures can't attack.

How it works : Peacekeeper

Original English text — Wizards of the Coast / Scryfall

#1April 1, 2008· Wizards of the Coast
When the ability resolves, you choose whether to sacrifice the creature or perform the other action. If you can’t perform the other action, then you must sacrifice the creature.
No other card is named in this ruling.
#2April 1, 2008· Wizards of the Coast
If the creature is no longer on the battlefield when the ability resolves, you may still perform the action if you want.
No other card is named in this ruling.
#3April 1, 2008· Wizards of the Coast
Peacekeeper’s ability doesn’t cause the combat phase or the declare attackers step to be skipped.
No other card is named in this ruling.

Interactions with other cards

These cards' text mentions Peacekeeper.

Custodi Peacekeeper

Reveal this card as you draft it and note how many cards you've drafted this draft round, including this card. {W}, {T}: Tap target creature with power less than or equal to the highest number you noted for cards named Custodi Peacekeeper.