Eliminate the Impossible {1}{U}
Instant
Investigate. Creatures your opponents control get -2/-0 until end of turn. If any of them are suspected, they're no longer suspected. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
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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.
Secrets of the Key 89%
$0.23#13388
"Investigate. If this spell was cast from a graveyard, investigate twice instead."
Kellan, Inquisitive Prodigy // Tail the Suspect 89%
$0.32#4405
"Investigate. You may play an additional land this turn."