Agrus Kos triggers, causing you to pay ({1} magic symbol) ({RW} magic symbol) to copy Soulbright Flamekin's ability targeting each other creature you control.
Resolve all Soulbright Flamekin triggers, giving the targeted creatures trample until end of turn and adding eight ({R} magic symbol) .
When Felidar Guardian enters the battlefield, it triggers, targeting Agrus Kos.
Agrus Kos triggers, causing you to pay ({1} magic symbol) ({RW} magic symbol) to copy Felidar Guardian's trigger, targeting each other creature you control except Felidar Guardian.
Resolve the copies of Felidar Guardian's trigger targeting Soulbright Flamekin and Skullwinder, blinking Soulbright Flamekin and Skullwinder.
When Skullwinder enters the battlefield, it triggers, returning Deflecting Swat from your graveyard to your hand and causing an opponent to return a card to their hand from their graveyard.
Agrus Kos triggers, causing you to pay ({1} magic symbol) ({RW} magic symbol) to copy Soulbright Flamekin's ability targeting each other creature you control.
Resolve all Soulbright Flamekin triggers, giving the targeted creatures trample until end of turn and adding eight ({R} magic symbol) .
Cast Deflecting Swat by paying ({0} magic symbol) , changing any of the remaining Felidar Guardian triggers not targeting Agrus Kos to target Agrus Kos instead.
Repeat from step 6.
Results
Infinite LTB.
Infinite ETB.
Infinite storm count.
Infinite red mana.
Infinite magecraft triggers.
Infinite blinking.
Target opponent returns all cards in their graveyard to their hand.