Rhystic Study 

Enchantment
Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.
click a line to search just that ability, click more to combine them
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.
Hermit of the Natterknolls // Lone Wolf of the Natterknolls 93%
$0.29#11973
"Whenever an opponent casts a spell during your turn, draw a card."
Mystic Remora 92%
$12.46#98
"Whenever an opponent casts a noncreature spell, you may draw a card unless that player pays {4}."
Mangara, the Diplomat 91%
$0.25#616
"Whenever an opponent casts their second spell each turn, draw a card."
Kraum, Ludevic's Opus 91%
#6811
"Whenever an opponent casts their second spell each turn, draw a card."
Ghostly Pilferer 90%
$3.49#1404
"Whenever an opponent casts a spell from anywhere other than their hand, draw a card."
Esper Sentinel 89%
$56.22#76
"Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is this creature's power."
Wavebreak Hippocamp 88%
$0.83#2329
"Whenever you cast your first spell during each opponent's turn, draw a card."
Lu Xun, Scholar General 83%
$0.34#16650
"Whenever this card deals damage to an opponent, you may draw a card."
Faerie Mastermind 82%
$10.74#317
"Whenever an opponent draws their second card each turn, you draw a card."