Wall of Lost Thoughts 

Creature — Wall
Defender (This creature can't attack.)
When this creature enters, target player mills four cards. (They put the top four cards of their library into their graveyard.)
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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.
Reito Sentinel 90%
$0.23#16004
"When this creature enters, target player mills three cards."
+1 more matching line
Watcher of the Wayside 86%
$0.21#15963
"When this creature enters, target player mills two cards. You gain 2 life."