Cheapest priced copy (Throne of Eldraine): $0.35 at Card Kingdom, near mint, their price list as of .
Mysterious Pathlighter 
Creature — Faerie · 2/2 · Uncommon · Throne of Eldraine · #22
Flying
Each creature you control that has an Adventure enters with an additional +1/+1 counter on it. (It doesn't need to have gone on the adventure first.)
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Throne of Eldraine | 22 | Uncommon | $0.35 | $0.49 |
3 rulings from Wizards of the Coast
- 4 October 2019If an effect refers to a card, spell, or permanent that has an Adventure, it won't find an instant or sorcery spell on the stack that's been cast as an Adventure.
- 4 October 2019A creature with an Adventure you control that would enter the battlefield with no +1/+1 counters on it enters with one +1/+1 counter on it.
- 4 October 2019An effect may refer to a card, spell, or permanent that "has an Adventure." This refers to a card, spell, or permanent that has an adventurer card's set of alternative characteristics, even if they're not being used and even if that card was never cast as an Adventure.