Text (SM+errata): You may cast target instant or sorcery card from an opponent's graveyard without paying its mana cost. [Oracle 2009/07/08]
If you want to play a card, it is played during the resolution of this spell. Timing restrictions (such as Sorcery) are ignored. Other restrictions (such as "play only during combat") are not ignored. [Shadowmoor FAQ 2008/04/21]
You can't pay any alternate costs, but you may pay additional costs (such as Conspire) if you choose. [Shadowmoor FAQ 2008/04/21]
