Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you cast an instant or sorcery spell, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.
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.
"Whenever you cast a noncreature spell, you may pay . If you do, tap target creature an opponent controls and it doesn't untap during its controller's next untap step."