Surreal Memoir

If a replacement effect would cause a spell with rebound that you cast from your hand to be put somewhere else instead of your graveyard (such as Leyline of the Void might), you choose whether to apply the rebound effect or the other effect as the spell resolves.

If you are unable to cast a card from exile this way, or you choose not to, nothing happens when the delayed triggered ability resolves. The card remains exiled for the rest of the game, and you won't get another chance to cast the card. The same is true if the ability is countered (due to Stifle, perhaps).

If you're playing a format involving only cards from the _Urza's Saga_(TM) set and later, you may change the order of your graveyard at any time. That means the easiest way to choose an instant card at random from your graveyard is to take all the instant cards in your graveyard, turn them face down, shuffle them, and pick a card. Then you just put the rest back.

At the beginning of your upkeep, all delayed triggered abilities created by rebound effects trigger. You may handle them in any order. If you want to cast a card this way, you do so as part of the resolution of its delayed triggered ability. Timing restrictions based on the card's type (if it's a sorcery) are ignored. Other restrictions are not (such as the one from Rule of Law).

If you're playing a format involving cards printed earlier than the _Urza's Saga_ set, you may not reorder your graveyard. In this case, you need to be more careful when selecting an instant card at random, perhaps by using dice, writing the names of the instant cards on slips of paper and choosing one of them randomly, or carefully noting the existing graveyard order so you can reestablish it after performing the method suggested above, for example.

If you have only one instant card in your graveyard as Surreal Memoir resolves, that's the one you'll return to your hand.