Nightstalker Engine 

Creature — Nightstalker
Nightstalker Engine's power is equal to the number of creature cards in your 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.
Urborg Lhurgoyf 94%
$0.31#14287
"this card's power is equal to the number of creature cards in your graveyard and its toughness is equal to that number plus 1."
Splinterfright 93%
$0.27#5157
"this card's power and toughness are each equal to the number of creature cards in your graveyard."
Boneyard Wurm 93%
$0.28#13650
"this card's power and toughness are each equal to the number of creature cards in your graveyard."
Old Stickfingers 93%
$0.42#3857
"this card's power and toughness are each equal to the number of creature cards in your graveyard."
Revenant 93%
$0.17#18797
"this card's power and toughness are each equal to the number of creature cards in your graveyard."
Boneyard Mycodrax 91%
$0.31#14949
"this card's power and toughness are each equal to the number of other creature cards in your graveyard."
Apocalypse Demon 85%
$0.28#15673
"this card's power and toughness are each equal to the number of cards in your graveyard."
Duelist of the Mind 82%
$0.29#10170
"this card's power is equal to the number of cards you've drawn this turn."
Archpriest of Iona 81%
$0.33#10649
"this card's power is equal to the number of creatures in your party."
Sewer Nemesis 80%
$1.20#5884
"this card's power and toughness are each equal to the number of cards in the chosen player's graveyard."