Cheapest priced copy (Modern Horizons): $0.35 at Card Kingdom, near mint, their price list as of .
Conifer Wurm 
Snow Creature — Wurm · 4/4 · Uncommon · Modern Horizons · #159
Trample
{3}{G}: This creature gets +X/+X until end of turn, where X is the number of snow permanents you control.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.35 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Modern Horizons | 159 | Uncommon | $0.35 | $0.79 |
2 rulings from Wizards of the Coast
- 14 June 2019Because Conifer Wurm is itself a snow permanent, its ability will usually give it at least +1/+1.
- 14 June 2019The value of X is determined only as Conifer Wurm's ability begins to resolve. It won't change later in the turn if the number of snow permanents you control changes.