Cheapest priced copy (Darksteel): $0.59 at Card Kingdom, near mint, their price list as of .
Arcbound Slith 
Artifact Creature — Slith · 0/0 · Uncommon · Darksteel · #102
Whenever this creature deals combat damage to a player, put a +1/+1 counter on it.
Modular 1 (This creature enters with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
3 printings · $0.59 to $4.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Darksteel | 102 | Uncommon | $0.59 | $4.99 |
| Planechase | 106 | Uncommon | $0.59 | — |
| The List | DST-102 | Uncommon | $0.69 | — |
One ruling from Wizards of the Coast
- 25 September 2006If this creature gets enough -1/-1 counters put on it to cause its toughness to be 0 or less (or the damage marked on it to be lethal), modular will put a number of +1/+1 counters on the target artifact creature equal to the number of +1/+1 counters on this creature before it left the battlefield.