Keeper of the Dead {B}{B}
Creature — Human Wizard
{B}, {T}: Choose target opponent who has at least two fewer creature cards in their graveyard than you do as you activate this ability. Destroy target nonblack creature that player controls.
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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.