Some thoughts:

• i think your current creature selection require far too much mana to be useful. Ideally in a prowess deck you want to be as-low-to-the-ground as possible, so you can apply pressure early and secure a fast win. I’d suggest ditching all your creatures that cost 3-or-more mana. Replacements to consider include Monastery Swiftspear, Soul-Scar Mage and Sprite Dragon. If you’re able to afford Manamorphose, then Stormwing Entity becomes a good pick also. You probably only want your creature count to be around 18-19.

• I don’t know why Unstable Mutation is here.

• For some more useful spells, i’d suggest Gut Shot, Lava Dart, Lightning Bolt, and Mutagenic Growth. I’d advise on not using cards like Counterspell, as they generally don’t help your creatures get anywhere useful (its a potential sideboard card).

Thanks for the comment, reworked the deck and added a sizeable maybeboard, much much faster now :D

My brother runs a similar list... as mentioned before/above Manamorphose is really really good to put in here... Remand is also a neat card because you can target your own spells... get the prowess trigger/draw and keep casting.

Cool deck idea!

Here's some things I would change:
1) Most lines that play out with this archetype involve playing a payoff creature on turn 1 (and having the flexibility to play two of those creature on turn two). Playing a Young Pyromancer on turn two is fine, but in general you want to lay down your payoffs for these cheap spells as early as possible. Having 16 two mana creatures is just way too clunky. I would recommend at least including Soul-Scar Mage because it's a Wizard. Which brings me to my next point.
2) Since you're already running a Wizard-themed deck, you should at least include the good Wizard payoffs (some of which are actually played in modern). These are Flame of Anor and Wizard's Lightning, the latter of which is essentially just Lightning Bolt 5-8. But I see you only play 3 of those which brings me to my last point.
3) You need to condense your card selections down to playsets of the most important cards, if you can. The reason people play mostly 4-ofs in proactive, aggro-based strategies is because in induces consistency. If card accessibility is an issue I can absolutely understand that. But try and look at the Izzet Prowess Modern Metagame and just take all the cards that are inexpensive from that list and try and incorporate them into the shell you created - especially the instants and sorceries, minus the few you already have.

Anyway, I hope this helps. Looks like fun though =)

Thanks for the advice! I condensed it down quite a bit and it's definitely a little more consistent