Corrosive Mentor 
Creature — Elemental Rogue
$7.00 #10341 0.44 18.5 years
Black creatures you control have wither. (They deal damage to creatures in the form of -1/-1 counters.)
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Cards similar to Corrosive Mentor 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.
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