Cheapest priced copy (Guilds of Ravnica): $0.35 at Card Kingdom, near mint, their price list as of .
Vigorspore Wurm 
Creature — Wurm · 6/4 · Common · Guilds of Ravnica · #147
Undergrowth — When this creature enters, target creature gains vigilance and gets +X/+X until end of turn, where X is the number of creature cards in your graveyard.
This creature can't be blocked by more than one creature.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Guilds of Ravnica | 147 | Common | $0.35 | $0.49 |
5 rulings from Wizards of the Coast
- 5 October 2018If there are no creature cards in your graveyard, the target creature just gains vigilance until end of turn.
- 5 October 2018Because tokens aren't cards, they never count for undergrowth abilities.
- 5 October 2018The value of X is determined only as the undergrowth ability resolves. If the number of creature cards in your graveyard changes later in the turn, the target creature is unaffected.
- 5 October 2018If Vigorspore Wurm gains menace, it can't be blocked at all.
- 5 October 2018Creature cards with other types, such as artifact creature cards, count for undergrowth abilities.