Cheapest priced copy (Fallen Empires): $0.59 at Card Kingdom, near mint, their price list as of .
Thelon's Curse 
Enchantment · Rare · Fallen Empires · #77
Blue creatures don't untap during their controllers' untap steps.
At the beginning of each player's upkeep, that player may choose any number of tapped blue creatures they control and pay {U} for each creature chosen this way. If the player does, untap those creatures.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $0.59 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Fallen Empires | 77 | Rare | $0.59 | — |