Who gains priority after a spell is cast?

When a spell is cast, the controller of that spell gains priority. This is an essential aspect of the game rules as it determines the order in which players can take actions following a spell being cast. The active player, who is the one whose turn it is, not only has the opportunity to cast spells but also to respond to other spells or abilities that may have been activated.

After a spell is announced, the game waits for that spell to resolve or for the active player to pass priority. If they choose to pass priority without taking any additional actions, it proceeds to the next player in turn order. However, initially, it is the spell's controller that holds priority, allowing them to respond or continue interacting with the game state.

Other options incorrectly imply relationships between players that do not align with the rules governing priority. The player to the left of the caster or any enemy player does not gain priority until the active player has passed their chance to act. Furthermore, even the player with the next turn would not gain priority until the current player's actions are fully resolved. Therefore, the correct answer emphasizes the importance of recognizing who has control over the game actions immediately after a spell is cast.