Until end of turn, whenever a player casts an instant or sorcery spell, that player copies it and may choose new targets for the copy.
The copy will have the same targets as the spell itâ€™s copying unless its controller chooses new ones. That player may change any number of the targets, including all of them or none of them. The new targets must be legal.
The copy that Bonus Roundâ€™s ability creates is created on the stack, so itâ€™s not â€œcast.â€ Abilities that trigger when a player casts a spell (like Bonus Roundâ€™s ability itself) wonâ€™t trigger.
The controller of the spell that caused Bonus Roundâ€™s ability to trigger also controls the copy.
The controller of the copy canâ€™t choose to pay any additional costs for the copy. However, effects based on any additional costs that were paid for the original spell are copied as though those same costs were paid for the copy too.
If the spell thatâ€™s copied is modal (that is, it says â€œChoose one â€”â€ or the like), the copy will have the same mode. Its controller canâ€™t choose a different one.
If the spell thatâ€™s copied has an X whose value was determined as it was cast, the copy has the same value of X.
Bonus Roundâ€™s ability will copy any instant or sorcery spell, not just one with targets.
A copy is created even if the spell that caused Bonus Roundâ€™s ability to trigger has been countered by the time that ability resolves. The copy resolves before the original spell.