Mudslide {2}{R}
Enchantment
Creatures without flying don't untap during their controllers' untap steps.
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.
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Cards that do something similar expected a card that isn't here?
Reports become test cases the matcher is graded against before an update ships. Delvefall isn't a chatbot guessing, it compares the printed rules text of every card with plain math, and examples like yours decide which differences should count.
Dream Tides 96%
$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
Magnetic Mountain 96%
$0.41#22770
"At the beginning of each player's upkeep, that player may choose any number of tapped blue creatures they control and pay {4} for each creature chosen this way. If the player does, untap those creatures."
+1 more matching line
Thelon's Curse 92%
$0.69#31147
"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."
+1 more matching line
Karona, False God 86%
$3.68#13514
"At the beginning of each player's upkeep, that player untaps this card and gains control of it."
An-Zerrin Ruins 82%
#21384
"Creatures of the chosen type don't untap during their controllers' untap steps."
Dazzling Theater // Prop Room 82%
$0.78#1835
"Untap each creature you control during each other player's untap step."
Brass Man 82%
#25713
"At the beginning of your upkeep, you may pay {1}. If you do, untap this creature."
+1 more matching line
Brass Gnat 82%
$0.08#22858
"At the beginning of your upkeep, you may pay {1}. If you do, untap this creature."
+1 more matching line
Goblin War Wagon 81%
$0.03#30078
"At the beginning of your upkeep, you may pay {2}. If you do, untap this creature."
+1 more matching line
Arena of the Ancients 80%
#18622
"Legendary creatures don't untap during their controllers' untap steps."
Goblin Dirigible 80%
$0.09#30884
"At the beginning of your upkeep, you may pay {4}. If you do, untap this creature."
+1 more matching line
White Plume Adventurer 80%
$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."
Walking Dream 80%
$0.19#31324
"This creature doesn't untap during your untap step if an opponent controls two or more creatures."