Mystic Barrier, and Estrid's Invocation

Prerequisites

• Mystic Barrier on the battlefield
• Estrid's Invocation on the battlefield
• You have at least two opponents

Steps

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

Results

• Creatures cannot attack