Breath of Fury attached to a creature you control except
Donatello that doesn't have summoning sickness).
Notable Prerequisites
An opponent cannot block creatures you control.
You control an artifact creature.
Steps
Deal combat damage to an opponent using
Donatello and the creature that has
Breath of Fury attached, triggering
Donatello and
Breath of Fury.
Resolve the
Donatello trigger, creating a token copy of the artifact creature.
Resolve the
Breath of Fury trigger, causing you to sacrifice the creature it is attached to, then attach
Breath of Fury to the artifact creature 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
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.
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-infinitely large creatures you control until end of turn.