Declare Raubahn and the creature with Breath of Fury attached as attackers.
Raubahn triggers, attaching Deathrender to the creature that has Breath of Fury attached.
Deal combat damage using the creature that has Breath of Fury attached. 
Breath of Fury triggers, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to the other creature that has haste, then causing you to untap all creatures you control and to get an additional combat phase after this one.
When the creature that had Breath of Fury attached dies, Ares and Deathrender trigger.
Resolve the Ares trigger, returning the creature from your graveyard to your hand.
Resolve the Deathrender trigger, putting the creature from your hand onto the battlefield and attaching Deathrender to it.
Repeat each combat phase.

Infinite creature ETB

Infinite creature LTB

Infinite combat damage

Infinite combat phases

Infinite death triggers

Infinite mana creatures you control can produce

Infinite creature sacrifice triggers

Infinite untap of creatures you control

Creature with Haste

Ares, God of War

Deathrender

Breath of Fury

Raubahn, Bull of Ala Mhigo

At the beginning of your combat phase, Ardenn triggers, attaching Breath of Fury and Deathrender to the creature with haste.
Deal combat damage using the creature that has Breath of Fury attached. 
Breath of Fury triggers, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to Ares, then causing you to untap all creatures you control and to get an additional combat phase after this one.
When the creature that had Breath of Fury attached dies, Ares and Deathrender trigger.
Resolve the Ares trigger, returning the creature from your graveyard to your hand.
Resolve the Deathrender trigger, putting the creature from your hand onto the battlefield and attaching Deathrender to it.
Repeat each combat phase.

Ardenn, Intrepid Archaeologist

At the beginning of your combat phase, Halvar triggers, attaching Breath of Fury to the creature with haste.
Deal combat damage using the creature that has Breath of Fury attached. 
Breath of Fury triggers, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to Ares, then causing you to untap all creatures you control and to get an additional combat phase after this one.
When the creature that had Breath of Fury attached dies, Ares and Deathrender trigger.
Resolve the Ares trigger, returning the creature from your graveyard to your hand.
Resolve the Deathrender trigger, putting the creature from your hand onto the battlefield and attaching Deathrender to it.
Repeat each combat phase.

Halvar, God of Battle // Sword of the Realms

Combos with "Ares, God of War"