Mystic Barrier, and Clever Impersonator

Prerequisites

• Mystic Barrier on the battlefield
• Clever Impersonator on the battlefield
• You have at least two opponents

Steps

1. At the beginning of each of your upkeeps, Mystic Barrier and Clever Impersonator trigger, choosing "left" for Mystic Barrier and "right" for Clever Impersonator
2. As long as there are three or more players in the game, creatures cannot attack

Results

• Creatures cannot attack