Heartless Hidetsugu without summoning sickness and
Pariah attached to any creature you control).
Easy Prerequisites
Each opponent's life total is 2 or greater.
Notable Prerequisites
Heartless Hidetsugu does not have summoning sickness
At least one opponent has an even life total
You have an odd life total.
Steps
Activate
Heartless Hidetsugu by tapping it, dealing damage to each opponent equal to half their life total, rounded down, times 2, and dealing no damage to you due to
Pariah.
Activate
Heartless Hidetsugu by tapping it, causing it to deal damage to each player equal to half their life total, rounded down, then doubled.
Each player who started with an even life ottal loses the game for having 0 or less life.
Notes
If the opponents have an odd life total, they will have 1 life remaining. If they have an even life total, they will have 0 life and lose the game.
Results
Near-infinite damage.
Each opponent with an even life total loses the game.