FOILCheapest priced copy (Fate Reforged Clash Pack): $0.49 at Card Kingdom, foil, near mint, their price list as of .
Necropolis Fiend 
Creature — Demon · 4/5 · Rare · Khans of Tarkir Promos · #82s
Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Flying
{X}, {T}, Exile X cards from your graveyard: Target creature gets -X/-X until end of turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Fate Reforged Clash Pack | 1 | Rare | — | $0.49 |
| Khans of Tarkir | 82 | Rare | $0.49 | $0.49 |
| Khans of Tarkir Promos | 82s | Rare | — | $0.49 |
| Tarkir: Dragonstorm Commander | 190 | Rare | $0.49 | — |
3 rulings from Wizards of the Coast
- 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.
- 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.