Thelon's Curse {G}{G}
Enchantment
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.
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Cards that do something similar expected a card that isn't here?
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Magnetic Mountain 100%
$0.41#22770
"Blue creatures don't untap during their controllers' untap steps."
+1 more matching line
Dream Tides 95%
$0.44#17778
"At the beginning of each player's upkeep, that player may choose any number of tapped nongreen creatures they control and pay {2} for each creature chosen this way. If the player does, untap those creatures."
+1 more matching line
Mudslide 92%
#19339
"At the beginning of each player's upkeep, that player may choose any number of tapped creatures without flying they control and pay {2} for each creature chosen this way. If the player does, untap those creatures."
+1 more matching line
Karona, False God 91%
$3.68#13514
"At the beginning of each player's upkeep, that player untaps this card and gains control of it."
An-Zerrin Ruins 85%
#21384
"Creatures of the chosen type don't untap during their controllers' untap steps."
Slicer, Hired Muscle // Slicer, High-Speed Antagonist 85%
$9.18#3316
"At the beginning of each opponent's upkeep, you may have that player gain control of this card until end of turn. If you do, untap this card, goad it, and it can't be sacrificed this turn. If you don't, convert it."
White Plume Adventurer 84%
$2.57#3202
"At the beginning of each opponent's upkeep, untap a creature you control. If you've completed a dungeon, untap all creatures you control instead."
Island Fish Jasconius 84%
$0.33#26231
"At the beginning of your upkeep, you may pay {U}{U}{U}. If you do, untap this creature."
+1 more matching line
Arena of the Ancients 83%
#18622
"Legendary creatures don't untap during their controllers' untap steps."
Assault Suit 83%
$0.27#4132
"At the beginning of each opponent's upkeep, you may have that player gain control of equipped creature until end of turn. If you do, untap it."
Walking Dream 81%
$0.19#31324
"This creature doesn't untap during your untap step if an opponent controls two or more creatures."
Damping Field 81%
$8.60#27078
"Players can't untap more than one artifact during their untap steps."
Raphael, Tag Team Tough 81%
$6.19#11735
"Whenever this card deals combat damage to a player for the first time each turn, untap all attacking creatures. After this combat phase, there is an additional combat phase."