Delightful Discovery {4}{U}
Instant
This spell costs {1} less to cast for each spell your opponents have cast this turn.
Scry 2, then draw two cards. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)
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.
Gnoll War Band 92%
$0.24#12487
"This spell costs {1} less to cast for each opponent who was dealt damage this turn."
Tithe Taker 90%
$0.35#7544
"During your turn, spells your opponents cast cost {1} more to cast and abilities your opponents activate cost {1} more to activate unless they're mana abilities."
Chandra's Incinerator 89%
$3.07#2569
"This spell costs {X} less to cast, where X is the total amount of noncombat damage dealt to your opponents this turn."
Fast Forward 87%
$0.36#9862
"This spell costs {1} less to cast for each opponent you attacked this turn."
Thrasta, Tempest's Roar 83%
$0.66#9357
"This spell costs {3} less to cast for each other spell cast this turn."