Rule 803.1 · Attack Left and Attack Right Options
Some multiplayer games use the optional attack left or attack right rules.
Subrules
If the attack left option is used, a player can attack only an opponent seated immediately to their left, a planeswalker that player controls, or a battle that player protects. If a player’s nearest opponent to the left is more than one seat away, the player can’t attack.
If the attack right option is used, a player can attack only an opponent seated immediately to their right, a planeswalker that player controls, or a battle that player protects. If a player’s nearest opponent to the right is more than one seat away, the player can’t attack.