Obscuring Aether 
Enchantment
Face-down creature spells you cast cost {1} less to cast.
{1}{G}: Turn this enchantment face down. (It becomes a 2/2 creature.)
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.
Kadena, Slinking Sorcerer 88%
#11854
"The first face-down creature spell you cast each turn costs {3} less to cast."
Nylea, Keen-Eyed 80%
$5.20#3463
"Creature spells you cast cost {1} less to cast."
+1 more matching line