Marsh Viper 

Creature — Snake
Whenever this creature deals damage to a player, that player gets two poison counters. (A player with ten or more poison counters loses the game.)
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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.
Fynn, the Fangbearer 88%
$0.19#2710
"Whenever a creature you control with deathtouch deals combat damage to a player, that player gets two poison counters."
Pit Scorpion 85%
$0.09#28152
"Whenever this creature deals damage to a player, that player gets a poison counter."
Sabertooth Cobra 84%
$0.18#19465
"Whenever this creature deals damage to a player, that player gets a poison counter. The player gets another poison counter at the beginning of their next upkeep unless they pay {2} before that step."