Inertia Bubble 

Enchantment — Aura
Enchant artifact
Enchanted artifact doesn't untap during its controller's untap step.
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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.
Ashnod's Battle Gear 87%
$0.20#30335
"You may choose not to untap this artifact during your untap step."
Vedalken Shackles 87%
$7.66#11447
"You may choose not to untap this artifact during your untap step."
Deserter's Quarters 87%
$0.05#29280
"You may choose not to untap this artifact during your untap step."
Helm of Possession 87%
$5.07#14749
"You may choose not to untap this artifact during your untap step."