Ammit Eternal 

Creature — Zombie Crocodile Demon
Afflict 3 (Whenever this creature becomes blocked, defending player loses 3 life.)
Whenever an opponent casts a spell, put a -1/-1 counter on this creature.
Whenever this creature deals combat damage to a player, remove all -1/-1 counters from it.
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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.
Witherscale Wurm 95%
$0.80#19636
"Whenever this creature deals damage to an opponent, remove all -1/-1 counters from it."
Magmaroth 89%
$0.10#29030
"Whenever you cast a noncreature spell, remove a -1/-1 counter from this creature."
+1 more matching line
Sturdy Hatchling 87%
$0.13#28241
"Whenever you cast a blue spell, remove a -1/-1 counter from this creature."
+1 more matching line
Shrewd Hatchling 87%
$0.08#27480
"Whenever you cast a blue spell, remove a -1/-1 counter from this creature."
+1 more matching line
Noxious Hatchling 86%
$0.39#19662
"Whenever you cast a black spell, remove a -1/-1 counter from this creature."
+1 more matching line
Voracious Hatchling 86%
$0.18#28967
"Whenever you cast a black spell, remove a -1/-1 counter from this creature."
+1 more matching line
Lichenthrope 86%
$0.60#28461
"If damage would be dealt to this creature, put that many -1/-1 counters on it instead."
+1 more matching line
Obelisk Spider 85%
$2.79#4921
"Whenever this creature deals combat damage to a creature, put a -1/-1 counter on that creature."
+1 more matching line
Soul-Scar Mage 84%
$0.81#12556
"If a source you control would deal noncombat damage to a creature an opponent controls, put that many -1/-1 counters on that creature instead."
Belligerent Hatchling 84%
$0.18#28044
"Whenever you cast a red spell, remove a -1/-1 counter from this creature."
+1 more matching line