I understand the utility of
Vivid Marsh, but it's a bad land. It invariably enters tapped and only makes any color of mana twice unless you can proliferate, which this deck can't. People usually run
Vivid Marsh as a budget land when they can't afford better, but your deck has fetchlands and OG duals, so it doesn't make sense here. Same with
Bojuka Bog,
Temple of the False God, the bounce lands, etc... If you want a budget mana base, cut out the fetch lands and duals. If you want an optimized mana base, you should cut out the cheap bad lands and replace them with shocks (
Steam Vents), good any-color lands (
Mana Confluence,
City of Brass), and utility lands that don't enter tapped.
Again, with Niv-Mizzet, why not just run
Niv-Mizzet, the Firemind? It combos with
Curiosity, but is easier to cast. The version you're currently running doesn't seem to be worth the awkward mana cost.
Outside of the mana base, you also have plenty of other cards that you should upgrade before using duals. OG dual lands are probably the last thing that you should upgrade to, given that they are incredibly expensive for the added utility they provide. On the other hand, you're running cards like
Diabolic Tutor and
Magus of the Jar. Both of those cards have better, but more expensive, versions that you should use before spending several hundred dollars on a land. (For the record,
Vampiric Tutor and
Memory Jar.) I'm not saying this to criticize your deck building skills as much as to save you money. Why spend a ton of money to make your deck slightly better when you could spend half as much to make it much better?