Opal Acrolith {2}{W}
Enchantment
Whenever an opponent casts a creature spell, if this permanent is an enchantment, it becomes a 2/4 Soldier creature.
{0}: This permanent becomes an enchantment.
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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.