Of the two commanders, Mishra makes the most sense to be the leader of an upgraded precon: he cares specifically about noncreature artifacts and the precon was essentially made for him in mind, so upgrading the deck with him in mind would be its natural progression
However, he is perhaps best known for his casting of Fire at a pivotal moment in Final Fantasy IX
Assuming you have nine mana, you simply use Elite Arcanist to cast the Glorious End on each of your opponent's upkeeps, which in turn untaps your Elite Arcanist with Paradox Engine
The Zimone, Mystery Unraveler uses Landfall to trigger Manifest Dread, making it the other main mechanic within the Duskmourn Precon
5 Planechase Plane cards Promos exist, and were distributed at different events
Finally pricing changes, the market changes so make sure you consider that