Breaching Hippocamp 

Creature — Horse Fish
Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, untap another target creature you control.
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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.
Goatnapper 84%
$0.15#27920
"When this creature enters, untap target Goat and gain control of it until end of turn. It gains haste until end of turn."
Corridor Monitor 80%
$0.16#8938
"When this creature enters, untap target artifact or creature you control."