Cast Fraying Omnipotence by paying ({3} magic symbol) ({B} magic symbol) ({B} magic symbol) , causing each player to lose half their life, then discard half the cards in their hand, then sacrifice half the creatures they control, rounding up each time.
At the beginning of your end step, Wound Reflection triggers, causing each opponent to lose life equal to the life they have lost this turn.
Each opponent loses the game due to having zero or less life.