2017-04-18 : If the card has X in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.

2017-04-18 : If the exiled card is a land card, you may play it only if you have an available land play this turn.

2017-04-18 : If you cast a card “without paying its mana cost,” you can't choose to cast it for any alternative costs, such as emerge costs. You can, however, pay additional costs. If the card has any mandatory additional costs, such as that of Tormenting Voice, those must be paid to cast the card.

2017-04-18 : If you don't play the card, it will remain exiled.

2017-04-18 : Playing a card exiled with Oracle's Vault follows the normal timing rules for playing that card. For example, if the card is a creature card, you can cast that card only during your main phase while the stack is empty.

2017-04-18 : The cards exiled by Oracle's Vault are exiled face up.

2017-04-18 : The first ability of Oracle's Vault puts a brick counter on it even if you can't or don't play the card.

2017-04-18 : You may play the exiled card this turn even if Oracle's Vault is no longer on the battlefield or under your control.