Taigam, Ojutai Master

At the beginning of your upkeep, all delayed triggered abilities created by rebound effects trigger. You may handle them in any order. A spell you cast this way resolves before you can cast the next one, so one rebounded spell can't target another. Timing permissions based on the card's type (if it's a sorcery) are ignored. Other restrictions, such as "Cast [this spell] only during combat," must be followed.

Casting the card again due to rebound's delayed triggered ability is optional. If you choose not to cast the card, or if you can't (perhaps because there are no legal targets available), the card will stay exiled. You won't get another chance to cast it on a future turn.

If a spell with rebound that you cast from your hand doesn't resolve for any reason (either because another spell or ability counters it or because all its targets are illegal as it tries to resolve), none of its effects will happen, including rebound. The spell will be put into its owner's graveyard and you won't get to cast it again on your next turn.