Im sure this will be yet another weird Commander buildaround, but I think Niv-Mizzet, Guildpact mostly wants to hang out in the graveyard waiting to get pulled along by your Lazav, Wearer of Faces, like Weekend at Bernies 2: Guildpact Edition
But in actuality, the Faithless Looting mode is pure upside, and youre only using it for card disadvantage when it is advantageous for you to do so
The deck is absolutely going to be high risk, possible higher reward and I think this Phyrexian will absolutely entice the audience its meant for
Aim for redundancy: Multiple cards that do similar jobs
Your opponents will quickly find themselves unable to compete
If the result is the chaos symbol, they activate the chaos effect of the active plane card