Phyrexian Slayer 

Creature — Phyrexian Minion
Flying
Whenever this creature becomes blocked by a white creature, destroy that creature. It can't be regenerated.
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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.
Evil Eye of Urborg 90%
$0.24#11870
"Whenever this creature becomes blocked by a creature, destroy that creature."
Sylvan Basilisk 90%
$0.36#24347
"Whenever this creature becomes blocked by a creature, destroy that creature."
Phyrexian Reaper 88%
$0.10#30076
"Whenever this creature becomes blocked by a green creature, destroy that creature. It can't be regenerated."
Ogre Leadfoot 82%
$0.03#30965
"Whenever this creature becomes blocked by an artifact creature, destroy that creature."
Stinkweed Imp 81%
$1.80#3062
"Whenever this creature deals combat damage to a creature, destroy that creature."
Voracious Cobra 81%
$0.28#26609
"Whenever this creature deals combat damage to a creature, destroy that creature."
Dripping Dead 80%
$0.16#30259
"Whenever this creature deals combat damage to a creature, destroy that creature. It can't be regenerated."
Grotesque Hybrid 80%
$0.22#28027
"Whenever this creature deals combat damage to a creature, destroy that creature. It can't be regenerated."
Mephitic Ooze 80%
$0.54#24995
"Whenever this creature deals combat damage to a creature, destroy that creature. The creature can't be regenerated."
Infernal Medusa 80%
$5.93#26814
"Whenever this creature becomes blocked by a non-Wall creature, destroy that creature at end of combat."