Who determines the timestamp order if two or more effects receive timestamps simultaneously?

The correct answer is that the active player determines the timestamp order if two or more effects receive timestamps simultaneously. In Magic: The Gathering, the concept of timestamps is crucial in establishing the order in which effects are applied, particularly when multiple effects are created at the same time.

When effects or objects reach the battlefield or are otherwise created simultaneously, the active player (the player whose turn it is) will determine the order of these effects. This is essential because the order can affect how the game state and interactions unfold, especially if those effects are dependent on each other.

For example, if both a creature and an enchantment enter the battlefield at the same time, the active player decides which one receives the earlier timestamp. This is important in scenarios where abilities may be contingent on the existence or timing of other permanents, such as when resolving combat damage or applying various continuous effects.

The involvement of the active player in this situation emphasizes their role in controlling the game during their turn, including the management of how simultaneous effects manifest on the battlefield.