Myr Superion 
Artifact Creature — Myr
$2.57 #10487 0.00 15.4 years
Spend only mana produced by creatures to cast this spell.
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Cards similar to Myr Superion 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.
Imperiosaur86%
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"You may pay 
rather than pay this spell's mana cost. Spend only mana produced by Treasures to cast it this way."
rather than pay this spell's mana cost. Spend only mana produced by Treasures to cast it this way."
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"You can't spend mana to cast this spell."
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"Spend only black mana on X."
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$0.16↓#15915↓0.40↑33.2 years↑
"Spend only black mana on X."