Nafs Asp 
Creature — Snake
Whenever this creature deals damage to a player, that player loses 1 life at the beginning of their next draw step unless they pay {1} before that draw step.
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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.
Glass Asp 95%
$0.17#27109
"Whenever this creature deals combat damage to a player, that player loses 2 life at the beginning of their next draw step unless they pay {2} before that step."
Death Charmer 89%
$0.10#28469
"Whenever this creature deals combat damage to a creature, that creature's controller loses 2 life unless they pay {2}."
Thrashing Mudspawn 87%
$0.11#28401
"Whenever this creature is dealt damage, you lose that much life."
Archfiend of Spite 87%
$0.80#8958
"Whenever a source an opponent controls deals damage to this creature, that source's controller loses that much life unless they sacrifice that many permanents of their choice."
Emissary of Despair 86%
$0.14#20389
"Whenever this creature deals combat damage to a player, that player loses 1 life for each artifact they control."
Vedalken Ghoul 86%
$0.21#27008
"Whenever this creature becomes blocked, defending player loses 4 life."
Ashenmoor Liege 85%
$0.43#15977
"Whenever this creature becomes the target of a spell or ability an opponent controls, that player loses 4 life."
Flayed Nim 85%
$0.14#24376
"Whenever this creature deals combat damage to a creature, that creature's controller loses that much life."
Vicious Battlerager 85%
$0.16#11090
"Whenever this creature becomes blocked by a creature, that creature's controller loses 5 life."
Dragonlord Kolaghan 85%
$11.95#7710
"Whenever an opponent casts a creature or planeswalker spell with the same name as a card in their graveyard, that player loses 10 life."
Neko-Te 84%
$5.09#18717
"Whenever equipped creature deals damage to a player, that player loses 1 life."
Sower of Discord 82%
$5.20#3515
"Whenever damage is dealt to one of the chosen players, the other chosen player also loses that much life."
Bebop, Skull & Crossbones 82%
$0.26#10788
"Whenever this card deals combat damage to a player, you may draw X cards, where X is the number of counters on this card. If you do, you lose X life."
Isolation Cell 82%
$0.34#12315
"Whenever an opponent casts a creature spell, that player loses 2 life unless they pay {2}."
Guiltfeeder 82%
$1.44#6718
"Whenever this creature attacks and isn't blocked, defending player loses 1 life for each card in their graveyard."
Sarevok, Deathbringer 81%
$0.17#13864
"At the beginning of each player's end step, if no permanents left the battlefield this turn, that player loses X life, where X is this card's power."
Marionette Apprentice 81%
$0.83#560
"Whenever another creature or artifact you control is put into a graveyard from the battlefield, each opponent loses 1 life."