Miracle card says to "play" any spell, not acquire. After casting the miracled spell, does the caster discard/recharge it or does the spell go away?
The spell, in its FAQ'd form, says
Bury this card and expend a mythic charge to choose a spell from the box and summon and play it.
EDIT: Took out uncertain opinion because Zhayne nailed it.
From the FAQ:
What does "summon and play" mean?
Resolution: On page 15 of the rulebook, under Summoning and Adding Cards, add the following as a new paragraph following the paragraph about "summon and build."
If you are instructed to summon and play a card, immediately draw the card from the box and play it, using any power on it that can be used in the current circumstance, then banish it. If no power on it can be used in the current circumstance, banish it.