Haakon, Stromgald Scourge + Morophon, the Boundless + Nameless Inversion + Rowan, Scion of War

Prerequisites

• You've lost life this turn.

Steps

1. 1Activate Rowan by tapping it, causing black and red spells you cast to cost less for each life you've lost this turn.
2. 2Cast Nameless Inversion from your graveyard, as it is a Knight card, by paying due to Rowan and Morophon, giving a creature +3/-3 until end of turn.
3. 3If the creature has toughness 0 or less, the creature dies as a state-based action.
4. 4Repeat from step 2 as desired.

Effects

• Reduce the toughness of creatures opponents control to 0
• Reduce the toughness of each creature opponents control to 0 upon entering