Cheapest priced copy (Lorwyn Eclipsed Commander): $0.35 at Card Kingdom, near mint, their price list as of .
Risen Reef 
Creature — Elemental · 1/1 · Uncommon · The List · #M20-217
Whenever this creature or another Elemental you control enters, look at the top card of your library. If it's a land card, you may put it onto the battlefield tapped. If you don't put the card onto the battlefield, put it into your hand.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
5 printings · $0.35 to $13.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Lorwyn Eclipsed Commander | 132 | Uncommon | $0.35 | — |
| Core Set 2020 | 217 | Uncommon | $0.35 | $5.99 |
| The List | M20-217 | Uncommon | $0.35 | — |
| Secret Lair Drop | 1257 | Rare | $13.99 | $13.99 |
| Special Guests | 143 | Mythic | $7.49 | $7.99 |
One ruling from Wizards of the Coast
- 12 July 2019If you put the card into your hand, you don't have to reveal it. You also don't have to tell your opponent whether it's a nonland card or a land card you decided not to put onto the battlefield tapped.