Cheapest priced copy (Zendikar Rising): $0.35 at Card Kingdom, near mint, their price list as of .
Merfolk Windrobber 
Creature — Merfolk Rogue · 1/1 · Uncommon · Zendikar Rising · #70
Flying
Whenever this creature deals combat damage to a player, that player mills a card. (They put the top card of their library into their graveyard.)
Sacrifice this creature: Draw a card. Activate only if an opponent has eight or more cards in their graveyard.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Zendikar Rising | 70 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 25 September 2020An ability that offers a bonus if an opponent has eight or more cards in their graveyard won’t provide additional benefits if more than one opponent has eight or more cards in their graveyard. There are also no additional benefits no matter how many cards are in an opponent’s graveyard, as long as there are at least eight.
- 25 September 2020In a multiplayer game, once an opponent leaves the game, they won’t be considered for such an effect, no matter how many cards they had in their graveyard before leaving the game.