Whenever Mr. Foxglove attacks, draw cards equal to the number of cards in defending player's hand minus the number of cards in your hand. If you didn't draw cards this way, you may put a creature card from your hand onto the battlefield.
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 this creature attacks, you may put a creature card with mana value X or less from your hand onto the battlefield tapped and attacking, where X is the number of attacking creatures you control."