Cast Mirrorweave by paying {2}{W/U}{W/U}, causing each other creature to become a copy of It That Betrays until end of turn.
Sacrifice Bronze Bombshell by any method, triggering each It That Betrays controlled by an opponent.
Resolve one of the It the Betrays triggers, causing an opponent to put Bronze Bombshell from your graveyard onto the battlefield under their control.
Bronze Bombshell triggers, causing its controller to sacrifice it and dealing 7 damage to its controller.
Each It That Betrays not controlled by Bronze Bombshell's controller triggers, with your triggers being below each opponent's triggers.
Repeat from step 3.

Near-infinite damage

It That Betrays

Mirrorweave

Bronze Bombshell

Cast Fractured Identity by paying {3}{W}{U}, exiling It That Betrays and causing each opponent to create a token copy of it.
Sacrifice Bronze Bombshell by any method, triggering each It That Betrays controlled by an opponent.
Resolve one of the It the Betrays triggers, causing an opponent to put Bronze Bombshell from your graveyard onto the battlefield under their control.
Bronze Bombshell triggers, causing its controller to sacrifice it and dealing 7 damage to its controller.
Each It That Betrays not controlled by Bronze Bombshell's controller triggers.
Repeat from step 3.

Combos with "It That Betrays"