Cheapest priced copy (Fifth Dawn): $0.35 at Card Kingdom, near mint, their price list as of .
Skullcage 
Artifact · Uncommon · Fifth Dawn · #151
At the beginning of each opponent's upkeep, this artifact deals 2 damage to that player unless they have exactly three or exactly four cards in hand.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
2 printings · $0.35 to $1.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Fifth Dawn | 151 | Uncommon | $0.35 | $1.49 |
| Archenemy | 115 | Uncommon | $0.69 | — |
2 rulings from Wizards of the Coast
- 1 December 2004Skullcage’s ability deals damage if the player has zero, one, two, five, or more than five cards in hand when its ability resolves.
- 1 December 2004Skullcage doesn’t check hand size when it triggers, only when it resolves.