If the exiled card is a split card, then X is determined by the combined mana cost of both halves. However, when you cast the copy, you choose only one half to cast. You may cast a different half each time you create and cast a copy.
Elite Arcanist
If the copied card has {X} in its mana cost, you must choose 0 as its value when casting the copy. Don't confuse that {X} with the {X} in the activation cost of Elite Arcanist's ability.
The copy is created in and cast from exile. You must still follow any timing restrictions, such as "Cast [this spell] only during combat."
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. James Zapata
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
