Cheapest priced copy (The List): $0.49 at Card Kingdom, near mint, their price list as of .
Tombstalker 
Creature — Demon · 5/5 · Rare · Future Sight · #91
Flying
Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
4 printings · $0.49 to $14.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Future Sight | 91 | Rare | $0.79 | $14.99 |
| Modern Masters | 102 | Rare | $0.79 | $0.79 |
| The List | FUT-91 | Rare | $0.49 | — |
| Time Spiral Remastered | 146 | Rare | $0.49 | $0.49 |
3 rulings from Wizards of the Coast
- 19 March 2021Delve doesn't change a spell's mana cost or mana value. For example, Treasure Cruise's mana value is 8 even if you exiled three cards to cast it.
- 19 March 2021Because delve isn't an alternative cost, it can be used in conjunction with alternative costs, such as flashback. It can also be used to pay for additional costs that include generic mana.
- 19 March 2021You can exile cards to pay only for generic mana, and you can't exile more cards than the generic mana requirement of a spell with delve. For example, you can't exile more than seven cards from your graveyard to cast Treasure Cruise unless an effect has increased its cost.