Breath of Fury attached to another creature you control that has base power 0 that doesn't have summoning sickness.
An opponent cannot block creatures you control.
Steps
Deal combat damage to an opponent using the creature that has
Breath of Fury attached, triggering
Breath of Fury and
Primo.
Resolve the
Primo trigger, creating a 0/0 Fractal creature token that enters with a number of +1/+1 counters on it equal to the damage dealt.
Resolve the
Breath of Fury trigger, causing you to sacrifice the creature it is attached to and attach it to the Fractal token, then causing you to untap all creatures you control and to get an additional combat phase after this one.
Repeat each combat phase.
Results
Infinite card draw for all players.
Infinite draw triggers.
Infinite draw triggers for all players.
Near-infinite ETB.
Near-infinite LTB.
Near-infinite combat damage.
Near-infinite combat phases.
Near-infinite creature tokens.
Near-infinite death triggers.
Near-infinite mana creatures you control can produce.
Near-infinite sacrifice triggers.
Near-infinite untap of creatures you control.
Near-infinitely large creatures you control until end of turn.
Metadata
In 0 decks according to EDHREC.
Bracket Tag
This combo has been estimated to be Exhibition (Bracket 1+).