Before you shuffle your deck to start the game, you may reveal this card from your deck and exile an instant or sorcery card you drafted that isn't in your deck.
When Arcane Savant enters the battlefield, copy a card you exiled with cards named Arcane Savant. You may cast the copy without paying its mana cost.
8/23/2016 If you have more than one Arcane Savant in your deck, you may reveal any number of them and exile that many instant or sorcery cards you drafted that aren’t in your deck.
8/23/2016 As Arcane Savant’s last ability resolves, if there are multiple cards you exiled with cards named Arcane Savant, you choose one of them to copy.
8/23/2016 The copy is created in and cast from exile. You cast the copy during the resolution of Arcane Savant’s last ability. You ignore any timing restrictions based on the card type of the card you copied. However, you must still follow any other timing restrictions, such as “Cast [this spell] only during combat.”
8/23/2016 You can’t pay any alternative costs the card has. You can pay additional costs, and if the spell has any mandatory additional costs, you must pay those.
8/23/2016 If the copied card has in its mana cost, you must choose 0 as its value when casting the copy.