Cheapest priced copy (Tarkir: Dragonstorm Commander): $0.49 at Card Kingdom, near mint, their price list as of .
Twilight Drover 
Creature — Spirit · 1/1 · Rare · Duel Decks: Sorin vs. Tibalt · #9
Whenever a creature token leaves the battlefield, put a +1/+1 counter on this creature.
{2}{W}, Remove a +1/+1 counter from this creature: Create two 1/1 white Spirit creature tokens with flying.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
5 printings · $0.49 to $5.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Duel Decks: Sorin vs. Tibalt | 9 | Rare | $0.69 | — |
| Salvat 2005 | J37 | Rare | — | — |
| Ravnica: City of Guilds | 33 | Rare | $0.79 | $5.99 |
| Tarkir: Dragonstorm Commander | 136 | Rare | $0.49 | — |
| Crimson Vow Commander | 100 | Rare | $0.49 | — |
4 rulings from Wizards of the Coast
- 1 October 2005If Spirit tokens created by Twilight Drover leave the battlefield, they will trigger its first ability.
- 1 October 2005If a player leaves a multiplayer game, all creature tokens that player owns also leave the game. Twilight Drover's ability will trigger once per token.
- 1 October 2005Note that Twilight Drover doesn't have any way to sacrifice tokens or otherwise cause them to leave the battlefield.
- 1 October 2005The first ability only cares that creature tokens leave the battlefield. It doesn't matter where they went.