Before damage cast Ephemeral Shields, targeting any of the golems.
Precursor Golem's ability triggers, copying Shields to the other golems and giving each indestructible until the end of turn.
Cast Jeskai Charm, choosing the mode to give your creatures lifelink until the end of turn.
Cast Arcbond, targeting one of the golems.
Precursor Golem's ability triggers, copying Arcbond onto the other golems.
Once a Golem takes damage, the ability given by Arcbond triggers, reflecting the damage onto all players and all other creatures.
Because of lifelink, you gain life while all other players lose life.
As the ability deals damage to the other golems, their Arcbond abilities trigger in response, doing the same.

Infinite damage

Precursor Golem

Jeskai Charm

Ephemeral Shields

Arcbond

Cast Ephemeral Shields by paying {1}{W}, targeting Zada.
Zada triggers, creating a copy of Ephemeral Shields for each creature you control.
Resolve all Ephemeral Shields, giving all creatures you control indestructible until end of turn.
 Cast Jeskai Charm by paying {U}{R}{W}, giving all creatures you control +1/+1 and lifelink until end of turn.
Cast Arcbond by paying {2}{R}, targeting Zada.
Zada triggers, copying Arcbond for each creature you control.
Resolve each Arcbond, causing each creature you control to deal damage to each other creature and player when they are dealt damage.
Deal damage to any creature you control, triggering their Arcbond ability, dealing that much damage to each other creature and player.
The creature's lifelink triggers, causing you to gain life equal to the damage dealt.
When damage is dealt to each of your creatures, their Arcbond abilities will trigger.
Repeat from step 6 with each creature's trigger.

Each opponent loses the game

Infinite lifegain

Infinite lifegain triggers

Zada, Hedron Grinder

Before damage cast Ephemeral Shields, targeting any creature.
Mirrorwing Dragon's ability triggers, copying Shields to the other creatures and giving each indestructible until the end of turn.
Cast Jeskai Charm, choosing the mode to give your creatures lifelink until the end of turn.
Cast Arcbond, targeting one of the creatures.
Mirrorwing Dragon's ability triggers, copying Arcbond onto the other creatures.
Once a creature takes damage, the ability given by Arcbond triggers, reflecting the damage onto all players and all other creatures.
Because of lifelink, you gain life while all other players lose life.
As the ability deals damage to the other creatures you control, their Arcbond abilities trigger in response, doing the same.

Combos with "Ephemeral Shields"