Triumph of Saint Katherine

If you have fewer than six cards in your library or if Triumph of Saint Katherine isn't in your graveyard as the triggered ability resolves, no cards will be exiled and the ability will do nothing.

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.

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.

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

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

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.