Cheapest priced copy (Ixalan): $0.35 at Card Kingdom, near mint, their price list as of .
Wildgrowth Walker 
Creature — Elemental · 1/3 · Uncommon · Ixalan · #216
Whenever a creature you control explores, put a +1/+1 counter on this creature and you gain 3 life.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $2.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ixalan | 216 | Uncommon | $0.35 | $2.99 |
2 rulings from Wizards of the Coast
- 29 September 2017If a creature leaves the battlefield before an effect instructs it to explore, it still explores. Effects that trigger when a creature you control explores, such as that of Wildgrowth Walker, trigger if appropriate.
- 29 September 2017If Wildgrowth Walker leaves the battlefield while its triggered ability is on the stack, you won’t put a +1/+1 counter on anything but you will gain 3 life.