Cast Through Time — ruling 1

If a spell with rebound that you cast from your hand doesn’t resolve for any reason (due being countered by a spell like Cancel, or because all of its targets are illegal), rebound has no effect. The spell is simply put into your graveyard. You won’t get to cast it again next turn.

Cast Through Time — ruling 2

If you cast a spell with rebound from anywhere other than your hand (such as from your graveyard due to Sins of the Past, from your library due to cascade, or from your opponent’s hand due to Sen Triplets), rebound won’t have any effect. If you do cast it from your hand, rebound will work regardless of whether you paid its mana cost (for example, if you cast it from your hand due to Maelstrom Archangel).

Cast Through Time — ruling 3

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.

Cast Through Time — ruling 4

Rebound will have no effect on copies of spells because you don’t cast them from your hand.

Cast Through Time — ruling 5

If you cast a spell with rebound from your hand and it resolves, it isn’t put into your graveyard. Rather, it’s exiled directly from the stack. Effects that care about cards being put into your graveyard won’t do anything.

Cast Through Time — ruling 6

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).

Cast Through Time — ruling 7

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).

Cast Through Time — ruling 8

If you cast a card from exile this way, it will go to your graveyard when it resolves, fails to resolve, or is countered. It won’t go back to exile.

Cast Through Time : règles, fonctionnement et interactions (MTG)

Cast Through Time is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Instant and sorcery spells you control have rebound. (Exile the spell as it resolves if you cast it from your hand. At the beginning of your next upkeep, you may cast that card from exile without paying its mana cost.)

How it works : Cast Through Time

Original English text — Wizards of the Coast / Scryfall

#1June 15, 2010· Wizards of the Coast
If a spell with rebound that you cast from your hand doesn’t resolve for any reason (due being countered by a spell like Cancel, or because all of its targets are illegal), rebound has no effect. The spell is simply put into your graveyard. You won’t get to cast it again next turn.
No other card is named in this ruling.
#2June 15, 2010· Wizards of the Coast
If you cast a spell with rebound from anywhere other than your hand (such as from your graveyard due to Sins of the Past, from your library due to cascade, or from your opponent’s hand due to Sen Triplets), rebound won’t have any effect. If you do cast it from your hand, rebound will work regardless of whether you paid its mana cost (for example, if you cast it from your hand due to Maelstrom Archangel).
No other card is named in this ruling.
#3June 15, 2010· Wizards of the Coast
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.
No other card is named in this ruling.
#4June 15, 2010· Wizards of the Coast
Rebound will have no effect on copies of spells because you don’t cast them from your hand.
No other card is named in this ruling.
#5June 15, 2010· Wizards of the Coast
If you cast a spell with rebound from your hand and it resolves, it isn’t put into your graveyard. Rather, it’s exiled directly from the stack. Effects that care about cards being put into your graveyard won’t do anything.
No other card is named in this ruling.
#6June 15, 2010· Wizards of the Coast
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).
No other card is named in this ruling.
#7June 15, 2010· Wizards of the Coast
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).
No other card is named in this ruling.
#8June 15, 2010· Wizards of the Coast
If you cast a card from exile this way, it will go to your graveyard when it resolves, fails to resolve, or is countered. It won’t go back to exile.
No other card is named in this ruling.
#9June 15, 2010· Wizards of the Coast
Multiple instances of rebound on the same spell are redundant.
No other card is named in this ruling.
#10June 15, 2010· Wizards of the Coast
The rebound effect is not optional. Each instant and sorcery spell you cast from your hand is exiled instead of being put into your graveyard as it resolves, whether you want it to be or not. Casting the spell during your next upkeep is optional, however.
No other card is named in this ruling.
#11June 15, 2010· Wizards of the Coast
If a spell moves itself into another zone as part of its resolution (as Arc Blade, All Suns’ Dawn, and Beacon of Unrest do), rebound won’t get a chance to apply.
No other card is named in this ruling.
#12June 15, 2010· Wizards of the Coast
If a spell you cast from your hand has both rebound and buyback (and the buyback cost was paid), you choose which effect to apply as it resolves.
No other card is named in this ruling.
#13June 15, 2010· Wizards of the Coast
You’ll be able to cast a spell with flashback three times this way. First you can cast it from your hand. It will be exiled due to rebound as it resolves. Then you can cast it from exile due to rebound’s delayed triggered ability. It will be put into your graveyard as it resolves. Then you can cast it from your graveyard due to flashback. It will be exiled due to flashback as it resolves.
No other card is named in this ruling.
#14June 15, 2010· Wizards of the Coast
For the rebound effect to happen, Cast Through Time needs to be on the battlefield as the spell _finishes_ resolving. For example, if you cast Warp World from your hand, and as part of its resolution it puts Cast Through Time onto the battlefield, Warp World will rebound. Conversely, if Warp World shuffles your Cast Through Time into your library as part of its resolution, and doesn’t put another one onto the battlefield, it will not rebound.
No other card is named in this ruling.
#15June 15, 2010· Wizards of the Coast
If you cast an instant or sorcery spell from your hand and it’s exiled due to rebound, the delayed triggered ability will allow you to cast it during your next upkeep even if Cast Through Time has left the battlefield by then.
No other card is named in this ruling.
#16June 15, 2010· Wizards of the Coast
If you cast a card from exile “without paying its mana cost,” you can’t pay any alternative costs. Any X in the mana cost will be 0. On the other hand, if the card has optional additional costs (such as kicker or multikicker), you may pay those when you cast the card. If the card has mandatory additional costs (such as Momentous Fall does), you must pay those if you choose to cast the card.
No other card is named in this ruling.
#17June 15, 2010· Wizards of the Coast
If a spell has restrictions on when it can be cast (for example, “Cast [this spell] only during the declare blockers step”), those restrictions may prevent you from casting it from exile during your upkeep.
No other card is named in this ruling.
#18June 15, 2010· Wizards of the Coast
If you cast a spell using the madness or suspend abilities, you’re casting it from exile, not from your hand. Although those spells will have rebound, the ability won’t have any effect.
No other card is named in this ruling.
#19June 15, 2010· Wizards of the Coast
Similarly, if you gain control of an instant or sorcery spell with Commandeer, it will have rebound, but the ability won’t do anything because that spell wasn’t cast from your hand.
No other card is named in this ruling.