2023-04-14 : 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.

2023-04-14 : If you cast a card “without paying its mana cost,” you can’t pay any alternative costs. You can, however, pay additional costs. If the card has any mandatory additional costs, those must be paid to cast the card.

2023-04-14 : The card you cast may be one you just put into the graveyard with surveil or one already in the graveyard.

2023-04-14 : You choose whether or not to cast the instant or sorcery card as the triggered ability resolves. If you do, you do so as part of the resolution of that ability. You can’t wait to cast it later in the turn. Timing restrictions based on the card’s type are ignored.