Cheapest priced copy (Conflux): $0.99 at Card Kingdom, near mint, their price list as of .
Rotting Rats 
Creature — Zombie Rat · 1/1 · Common · Conflux · #51
When this creature enters, each player discards a card.
Unearth {1}{B} ({1}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
2 printings · $0.99 to $3.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Conflux | 51 | Common | $0.99 | $3.99 |
| Planechase | 39 | Common | $0.99 | — |
One ruling from Wizards of the Coast
- 1 February 2009When Rotting Rats's "enters" ability resolves, first the player whose turn it is chooses a card to discard, then each other player in turn order does the same, then all cards are discarded at the same time. No one sees what the other players are discarding before deciding which card to discard.