Cast Volcano Hellion by paying {2}{R}{R}.
Volcano Hellion enters the battlefield, triggering itself, targeting any other creature.
In response, cast Arcbond by paying {2}{R}, targeting the same creature and creating a delayed triggered ability.
Resolve Volcano Hellion's trigger, dealing an arbitrarily large amount of damage to the targeted creature and to you, reducing your life total to 1 due to Serra the Benevolent's emblem.
Arcbond's delayed triggered ability triggers, dealing an equal amount of damage to all other creatures and all players, which again does not reduce your life total below 1.

Infinite damage

Serra the Benevolent

Arcbond

Volcano Hellion

Cast Volcano Hellion by paying {2}{R}{R}.
Volcano Hellion enters the battlefield, triggering itself, dealing an arbitrarily large amount of damage to Coalhauler Swine and to you, which does not reduce your life total below 1 due to Serra the Benevolent's emblem.
Coalhauler Swine triggers, dealing an equal amount of damage to each player, which again does not reduce your life total below 1.

Combos with "Serra the Benevolent"