Shredder, Shadow Master + Archfiend of Despair

Prerequisites

• Opponents cannot block creatures you control.

Steps

1. 1Declare Shredder as an attacker. Shredder's first ability triggers, creating a tapped and attacking copy of it attacking each other opponent that isn't legendary.
2. 2Deal combat damage using the Shredders. Each Shredder triggers, causing each opponent to lose half their life total, rounded up.
3. 3At the beginning of your end step, Archfiend of Despair triggers, causing each opponent to lose life equal to the life they lost this turn. Each opponent then loses the game due to having 0 or less life.

Effects

• Each opponent loses the game
• Infinite lifeloss