Cheapest priced copy (Double Masters 2022): $0.39 at Card Kingdom, near mint, their price list as of .
Dark-Dweller Oracle 
Creature — Goblin Shaman · 2/2 · Common · Double Masters 2022 · #106
{1}, Sacrifice a creature: Exile the top card of your library. You may play that card this turn. (You still pay its costs. You can play a land this way only if you have an available land play remaining.)
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
5 printings · $0.39 to $2.29 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Double Masters 2022 | 106 | Common | $0.39 | $0.49 |
| Forgotten Realms Commander | 119 | Rare | $0.49 | — |
| Core Set 2019 | 134 | Rare | $0.49 | $0.49 |
| The List | 2X2-106 | Common | $0.39Out of stock | — |
| Core Set 2019 Promos | 134s | Rare | — | $2.29 |
4 rulings from Wizards of the Coast
- 13 July 2018You can sacrifice Dark-Dweller Oracle to pay the cost for its own ability.
- 13 July 2018Dark-Dweller Oracle doesn't change when you can cast the exiled card. For example, if you exile a sorcery card, you can cast it only during your main phase when the stack is empty. If you exile a land card, you can play it only during your main phase and only if you have an available land play remaining.
- 13 July 2018Casting an exiled card causes it to leave exile. You can't cast it multiple times.
- 13 July 2018If you don't cast the exiled card, it remains in exile.