Wizard's Spellbook

T: Exile target instant or sorcery card from a graveyard. Roll a d20. Activate only as a sorcery.
1-9 | Copy that card. You may cast the copy.
10-19 | Copy that card. You may cast the copy by paying 1 rather than paying its mana cost.
20 | Copy each card exiled with Wizard’s Spellbook. You may cast any number of the copies without paying their mana costs.