Cheapest priced copy (Ikoria: Lair of Behemoths): $0.49 at Card Kingdom, near mint, their price list as of .
Titans' Nest 
Enchantment · Rare · Ikoria: Lair of Behemoths · #212
At the beginning of your upkeep, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)
Exile a card from your graveyard: Add {C}. Spend this mana only to cast a spell that's one or more colors without {X} in its mana cost.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.49 to $2.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ikoria: Lair of Behemoths | 212 | Rare | $0.49 | $0.49 |
| Ikoria: Lair of Behemoths | 347 | Rare | $1.49 | $2.99 |
| Ikoria: Lair of Behemoths Promos | 212p | Rare | $0.49 | $0.49 |
| Ikoria: Lair of Behemoths Promos | 212s | Rare | — | $1.49 |
2 rulings from Wizards of the Coast
- 17 April 2020If you don’t put the card you look at into your graveyard, it remains on top of your library. You’ll draw it during your draw step unless something else moves it.
- 17 April 2020Mana produced by Titans’ Nest can be used to cast a spell that has {X} in an additional or alternative cost.