Cheapest priced copy (The Brothers' War Commander): $0.35 at Card Kingdom, near mint, their price list as of .
Mnemonic Sphere 
Artifact · Common · Kamigawa: Neon Dynasty · #64
{1}{U}, Sacrifice this artifact: Draw two cards.
Channel — {U}, Discard this card: Draw a card.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The Brothers' War Commander | 88 | Common | $0.35 | — |
| Kamigawa: Neon Dynasty | 64 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 18 February 2022Discarding the card is part of the cost to activate a channel ability.
- 18 February 2022If a channel ability requires a target, you may not activate it without a target just to discard the card.