Cheapest priced copy (Edge of Eternities): $0.35 at Card Kingdom, near mint, their price list as of .
Monoist Circuit-Feeder 
Artifact Creature — Nautilus · 4/4 · Uncommon · Edge of Eternities · #110
Flying
When this creature enters, until end of turn, target creature you control gets +X/+0 and target creature an opponent controls gets -0/-X, where X is the number of artifacts you control.
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Edge of Eternities | 110 | Uncommon | $0.35 | $0.49 |
3 rulings from Wizards of the Coast
- 25 July 2025If one target becomes illegal before Monoist Circuit-Feeder’s last ability resolves, the remaining legal target will still get +X/+0 or -0/-X, as appropriate.
- 25 July 2025The value of X is calculated only once, as Monoist Circuit-Feeder’s last ability resolves.
- 25 July 2025If you can’t choose both a creature you control and a creature an opponent controls as targets at the time Monoist Circuit-Feeder’s last ability is put onto the stack, the ability will be removed from the stack and none of its effects will occur.