Shriekgeist 

Creature — Spirit
Flying
Whenever this creature deals combat damage to a player, that player mills two cards.
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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.
Shadow Stinger 99%
$0.06#22688
"Whenever this creature deals combat damage to a player, that player mills three cards."
Screeching Silcaw 91%
$0.18#28760
"Whenever this creature deals combat damage to a player, if you control three or more artifacts, that player mills four cards."
Crosstown Courier 89%
$0.05#24345
"Whenever this creature deals combat damage to a player, that player mills that many cards."