If the spell that's copied has an X whose value was determined as it was cast, the copy will have the same value of X.
Reiterate
The copy will have the same targets as the spell it's copying unless you choose new ones. You may change any number of the targets, including all of them or none of them. If, for one of the targets, you can't choose a new legal target, then it remains unchanged (even if the current target is illegal).
If the spell that's copied is modal (that is, it says "Choose one —" or the like), the copy will have the same mode. A different mode can't be chosen.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Dan Murayama Scott
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