Magnetic Mountain 


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 {4} for each creature chosen this way. If the player does, untap those creatures.
click a line to search just that ability, click more to combine them
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.
Thelon's Curse 100%
$0.69#31147
"Blue creatures don't untap during their controllers' untap steps."
+1 more matching line
Dream Tides 99%
$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 96%
#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 87%
$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."
Brass Gnat 83%
$0.08#22858
"At the beginning of your upkeep, you may pay {1}. If you do, untap this creature."
+1 more matching line
Brass Man 83%
#25713
"At the beginning of your upkeep, you may pay {1}. If you do, untap this creature."
+1 more matching line
Goblin War Wagon 83%
$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 83%
#18622
"Legendary creatures don't untap during their controllers' untap steps."
Goblin Dirigible 83%
$0.09#30884
"At the beginning of your upkeep, you may pay {4}. If you do, untap this creature."
+1 more matching line
Walking Dream 81%
$0.19#31324
"This creature doesn't untap during your untap step if an opponent controls two or more creatures."
Assault Suit 81%
$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."
Mana Vault 81%
$113.72#145
"At the beginning of your upkeep, you may pay {4}. If you do, untap this artifact."
+1 more matching line
White Plume Adventurer 81%
$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."
Dazzling Theater // Prop Room 81%
$0.78#1835
"Untap each creature you control during each other player's untap step."
T-45 Power Armor 81%
$0.66#8517
"At the beginning of your upkeep, you may pay {E}. If you do, untap equipped creature, then put your choice of a menace, trample, or lifelink counter on it."