Cheapest priced copy (Commander Masters): $29.99 at Card Kingdom, near mint, their price list as of .
Darksteel Monolith 
Artifact · Rare · The Zeta Set · #344
Indestructible
Once each turn, you may pay {0} rather than pay the mana cost for a colorless spell you cast from your hand.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
5 printings · $29.99 to $54.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Masters | 743 | Rare | $29.99 | — |
| Commander Masters | 778 | Rare | $32.99 | $54.99 |
| The Zeta Set | 102 | Rare | — | — |
| The Zeta Set | 223 | Rare | — | — |
| The Zeta Set | 344 | Rare | — | — |
2 rulings from Wizards of the Coast
- 28 July 2023If you cast a card for an alternative cost of {0}, you can't pay any other alternative costs. You can, however, pay additional costs like kicker. If the card has any mandatory additional costs, you must pay those.
- 28 July 2023You must still follow any relevant timing rules for the colorless spell you cast from your hand.