One would probably want the spell to be signatured. In any case I contend that the miracle trick is too dependent on DM ruling in a way that makes wizards archivists.
I can do it with any caster capable of adding miracle to their spell list with access to circle magic. Bear in mind, I didn't say shadow miracle, I said miracle. As in real real major effect for free miracle :D SCM's just have a leg up on the competition.
"I live apart from you
But I know the things you do
No angel can save you, how?
You don't need a god, 'cause I'm here now."