Cheapest priced copy (Edge of Eternities Commander): $4.99 at Card Kingdom, near mint, their price list as of .
Horizon Explorer 
Creature — Insect Scout · 2/4 · Rare · Edge of Eternities Commander · #15
Lands you control enter untapped.
Whenever you attack a player, create a Lander token. (It's an artifact with "{2}, {T}, Sacrifice this token: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.")
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $4.99 to $5.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Edge of Eternities Commander | 15 | Rare | $4.99 | — |
| Edge of Eternities Commander | 35 | Rare | $5.49 | — |
2 rulings from Wizards of the Coast
- 25 July 2025If a land has an ability that says it enters tapped, you choose the order in which that ability’s effect and the effect of Horizon Explorer’s first ability apply. This means you can choose to have the land enter tapped or untapped. If a land you control is simply put onto the battlefield tapped without a replacement effect being applied, it always enters untapped if you control Horizon Explorer.
- 25 July 2025Horizon Explorer’s last ability will trigger once for each player you attack.