Prismatic Circle {2}{W}
Enchantment
Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
As this enchantment enters, choose a color.
{1}: The next time a source of your choice of the chosen color would deal damage to you this turn, prevent that damage.
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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.
Circle of Protection: Blue 85%
$0.16#21620
"{1}: The next time a blue source of your choice would deal damage to you this turn, prevent that damage."
Circle of Protection: Black 84%
$0.16#20427
"{1}: The next time a black source of your choice would deal damage to you this turn, prevent that damage."
Forcefield 81%
#17284
"{1}: The next time an unblocked creature of your choice would deal combat damage to you this turn, prevent all but 1 of that damage."