Essence Harvest 

Sorcery
Target player loses X life and you gain X life, where X is the greatest power among creatures you control.
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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.
Exotic Disease 98%
$0.26#29818
"Target player loses X life and you gain X life, where X is the number of basic land types among lands you control."
Vampire's Kiss 97%
$0.35#11221
"Target player loses 2 life and you gain 2 life. Create two Blood tokens."
Morsel Theft 94%
$0.18#26497
"Target player loses 3 life and you gain 3 life. If this spell's prowl cost was paid, draw a card."
Rhystic Syphon 80%
$0.20#28950
"Unless target player pays {3}, that player loses 5 life and you gain 5 life."