Breath of Fury + Mass Hysteria + Grave Titan

Breath of Fury

Mass Hysteria

Grave Titan

How it works

1. Declare the creature with Breath of Fury attached and Grave Titan as attackers.
2. Grave Titan triggers, creating a creature token.
3. Deal combat damage using the creature that has Breath of Fury attached.
4. Breath of Fury triggers, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to the creature token, then causing you to untap all creatures you control and to get an additional combat phase after this one.
5. Repeat each combat phase.

This vicious loop turns an ordinary attack into an unstoppable chain of extra turns by chaining combat phases together indefinitely. With Mass Hysteria granting haste to everything the moment it hits the battlefield, newly arriving threats don't have to wait to join the fray. You point Grave Titan and the creature enchanted by Breath of Fury at your opponent; each time that creature connects for combat damage, Breath of Fury triggers to sacrifice it, hop onto a fresh Zombie token produced by Grave Titan, and untap your entire board for another combat. Because Mass Hysteria ensures your new tokens can attack immediately, you can repeat this cycle endlessly to generate infinite combat phases and combat damage.