Cheapest priced copy (Avacyn Restored): $0.35 at Card Kingdom, near mint, their price list as of .
Yew Spirit 
Creature — Spirit Treefolk · 3/3 · Uncommon · Avacyn Restored · #207
{2}{G}{G}: This creature gets +X/+X until end of turn, where X is its power.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Avacyn Restored | 207 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 1 May 2012The value of X is determined when the ability resolves. The bonus won't change later in the turn if the creature's power changes.
- 14 July 2017If this creature's power is negative as its ability resolves, X is considered to be 0.