Cheapest priced copy (Dominaria United): $0.49 at Card Kingdom, near mint, their price list as of .
Anointed Peacekeeper 
Creature — Human Cleric · 3/3 · Rare · Dominaria United · #383
Vigilance
As this creature enters, look at an opponent's hand, then choose any card name.
Spells your opponents cast with the chosen name cost {2} more to cast.
Activated abilities of sources with the chosen name cost {2} more to activate unless they're mana abilities.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.49 to $5.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Dominaria United | 2 | Rare | $0.49 | $0.49 |
| Dominaria United | 383 | Rare | $0.79 | $0.99 |
| Dominaria United Promos | 2p | Rare | $0.49 | $5.99 |
| Dominaria United Promos | 2s | Rare | — | $1.79 |
6 rulings from Wizards of the Coast
- 9 September 2022Activated abilities contain a colon. They’re generally written “[Cost]: [Effect].” Some keyword abilities (such as equip) are activated abilities and will have colons in their reminder text. Triggered abilities (starting with “when,” “whenever,” or “at”) are unaffected by the last ability of Anointed Peacekeeper.
- 9 September 2022You can choose any card name, even if that card doesn’t normally have an activated ability. You’re not limited to the names of cards you saw in the opponent’s hand.
- 9 September 2022An activated mana ability is one that produces mana as it resolves, not one that costs mana to activate.
- 9 September 2022You can’t choose the name of a token unless that token has the same name as a card.
- 9 September 2022Anointed Peacekeeper’s last ability affects cards regardless of what zone they’re in. This includes cards in hands, cards in the graveyards, and exiled cards.
- 9 September 2022Anointed Peacekeeper’s third ability applies to all opponents, not just the opponent whose hand you looked at.