Who controls a copy of a spell or ability that was put on the stack?

When a copy of a spell or ability is put onto the stack, it is controlled by the player who placed it there. This principle is rooted in the Magic: The Gathering rules regarding copied spells and abilities, where control of a copy transfers based on the player who generated that copy.

For instance, if a player uses an effect that copies a spell, the copy is placed on the stack by that player, making them the controller of the new instance. This means that if you create a copy of an opponent's spell using an effect or ability, you are now the one controlling that copy of the spell. This concept emphasizes that the control of a game object, in this case, a copy, is determined by who actually performs the action of placing it on the stack.

Other options misinterpret the control of the copy. The original caster is only associated with the original spell, and while they may interact with the copy in various ways, they do not have control over it. Similarly, the player who last modified the spell could be further removed from the control once it is copied. Control is strictly related to who has placed the copy onto the stack, ensuring clarity in how spells and abilities function in gameplay.