Volcano Hellion enters the battlefield, triggering its ability, targeting any creature.
Holding priority, activate Brash Taunter's ability from Martyrdom any number of times by paying ({0} magic symbol) , causing any amount of damage that would be dealt to you to be dealt to Brash Taunter instead this turn.
Resolve the Volcano Hellion trigger from step 3, dealing an arbitrarily large amount of damage to the targeted creature and to Brash Taunter.
Brash Taunter triggers, targeting an opponent.
Holding priority, activate Brash Taunter's ability from Martyrdom many times by paying ({0} magic symbol) , causing the next large amount of damage that would be dealt to the targeted opponent to be dealt to Brash Taunter instead this turn.
Resolve Brash Taunter's ability, redirecting some of the damage back to Brash Taunter but still dealing lethal damage to the opponent.
Repeat from step 6 once for each remaining opponent.