|Sources||Guildpact, Dissension, Return to Ravnica|
Niv-Mizzet is the draconic leader and parun of the Izzet League and is at least 15,000 years old. His intellect exceeds the intellect of standard mortals by several echelons, and he is known for many ingenious inventions that currently serve the citizens of Ravnica, the most well known being the almost indestructible, yet easily usable and forgeable metal, mizzium.
 The Guildpact
As time wore on, he became further and further reclusive and wasn't seen publicly for over 2500 years prior to his appearance to help the goblin master engineer Crixizix deal with the rampant nephilim. He destroyed two of them, but fled after being injured by an unforseen attack by the nephilim, who had been empowered by consuming the flesh of a dragon. He left the battle, claiming that he was bored of the fight, for an unknown destination in the northern aeries and did not return whilst the Nephilim ran amok.
His disappearance from Ravnica seemed to be complete, as even those who were tied to the Firemind could not find him. However, he later returned as a signatory for the new guildpact negotiated by Teysa Karlov.
 The Firemind
The Firemind is an extrasensory link to Niv-Mizzet’s omniscience. To possess it is to be immersed in passionate brilliance. Not all Izzet are in tune with the Firemind though; the honor must be earned by passing a test or by accomplishing an extraordinary achievement.
- His card's flavor text "(Z->)90° - (E-N²W)90°t=1" is very well known, and has led to multiple interpretations; one such is that it reads "Niv-Mizzet = 1", as when one turns the symbols in the parenthesis 90 degrees, it reads "(NIV)-(MIZZE)t=1", a possible allusion that he considers himself #1 in every aspect, or that he is the only higher dragon left in Ravnica. Mark Rosewater's comment on the "=1" part was that this means "equal 1 copy of his name". Another interpretation is that his ability to tap to draw a card does 1 point of damage.
- It has been confirmed that he never left Ravnica, defusing the speculation that he could somehow planeswalk. 
 In-game references
Quoted or referred to:
- Crackling Perimeter
- Enter the Infinite
- Hypersonic Dragon
- Invoke the Firemind
- Izzet Guildgate (Dragon's Maze)
- Izzet Signet
- Nivix, Aerie of the Firemind
- Skinbrand Goblin
- Warmind Infantry