Cheapest priced copy (Hour of Devastation): $0.35 at Card Kingdom, near mint, their price list as of .
Ruin Rat 
Creature — Rat · 1/1 · Common · The List · #HOU-75
Deathtouch
When this creature dies, exile target card from an opponent's graveyard.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
2 printings · $0.35 to $0.59 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Hour of Devastation | 75 | Common | $0.35 | $0.49 |
| The List | HOU-75 | Common | $0.59 | — |
One ruling from Wizards of the Coast
- 14 July 2017If Ruin Rat dies at the same time as another creature, most likely because they were in combat together, its triggered ability can exile that other card.