Cheapest priced copy (Shadows over Innistrad): $0.39 at Card Kingdom, near mint, their price list as of .
Rancid Rats 
Creature — Zombie Rat · 1/1 · Common · Shadows over Innistrad · #130
Skulk (This creature can't be blocked by creatures with greater power.)
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.39 to $1.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Shadows over Innistrad | 130 | Common | $0.39 | $1.49 |
2 rulings from Wizards of the Coast
- 8 April 2016If you cause a creature to have 0 power or less, use the actual value (which may be negative) to determine whether it can block or be blocked. A creature with skulk and 0 or less power most likely won’t be blocked, but it won’t deal combat damage and won’t trigger any abilities that trigger when combat damage is dealt.
- 8 April 2016Skulk matters only as blockers are chosen. Modifying either creature’s power after blockers are chosen won’t cause the attacking creature to become unblocked.