"I shall seek the Emperor's forgiveness in the darkest places of the night."
—Oath the Penitent

Sister Repentia

Martyrdom — When Sister Repentia dies, you gain 2 life and draw two cards.
Miracle {W}{B} (You may cast this card for its miracle cost when you draw it if it's the first card you drew this turn.)

"I shall seek the Emperor's forgiveness in the darkest places of the night."
—Oath of the Penitent

Warhammer 40,000 Commander

If an effect puts a card into your hand without using the word "draw," the card wasn't drawn.

If the card with miracle leaves your hand before the triggered ability resolves, you won't be able to cast it using its miracle ability.

It's important to reveal a card with miracle before it is mixed with the other cards in your hand.

Miracle is an alternative cost to cast the spell with miracle. It can't be combined with other alternative costs, such as casting a spell "without paying its mana cost."

Multiple card draws are always treated as a sequence of individual card draws. For example, if you haven't drawn any cards yet during a turn and cast a spell that instructs you to draw three cards, you'll draw them one at a time. Only the first card drawn this way may be revealed and cast using its miracle ability.

To determine the total cost of a spell, start with the mana cost or alternative cost (such as a miracle cost) you're paying, add any cost increases, then apply any cost reductions. The mana value of the spell remains unchanged, no matter what the total cost to cast it was.

You can cast a card for its miracle cost only as the miracle triggered ability resolves. If you don't want to cast it at that time (or you can't cast it, perhaps because there are no legal targets available), you won't be able to cast it later for the miracle cost.

You can reveal and cast a card with miracle on any turn, not just your own, if it's the first card you've drawn that turn.

You cast the card with miracle during the resolution of the triggered ability. Ignore any timing rules based on the card's type.

You don't have to reveal a drawn card with miracle if you don't wish to cast it at that time.

You still draw the card, whether you use the miracle ability or not. Any ability that triggers whenever you draw a card, for example, will trigger. If you don't cast the card using its miracle ability, it will remain in your hand.