Cheapest priced copy (The List): $5.49 at Card Kingdom, near mint, their price list as of .
Acorn Catapult 
Artifact · Rare · Commander 2011 · #241
{1}, {T}: This artifact deals 1 damage to any target. That permanent's controller or that player creates a 1/1 green Squirrel creature token.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $5.49 to $6.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2011 | 241 | Rare | $6.49 | — |
| The List | CMD-241 | Rare | $5.49 | — |
2 rulings from Wizards of the Coast
- 22 September 2011If the ability resolves, but the damage is prevented or redirected, the targeted player or the controller of the targeted creature puts the Squirrel token onto the battlefield, regardless of how much damage was dealt or what the damage was ultimately dealt to.
- 22 September 2011If the permanent or player is an illegal target when the ability tries to resolve, it won't resolve and none of its effects will happen. No Squirrel will be created.