Disclaimer: Early Testing! Planning to build at least two more versions around the same idea (an unfair version with prismari command, ugin the spirit dragon and probably kiora bests the sea god. Also a Jeskai Midrange Version revolving around 4 Mana Narset if possible)

I'd love some constructive feedback from more experienced players as I have not played the archetype a lot so far.

Deck idea:

This deck is based on the Izzet Creativity decks that use Torrential Gearhulk to cast Opus and Sublime Epiphany from the graveyard. The Hellraiser is kind of similar to Torrential Gearhulk with a couple of interesting differences. First: If the graveyard is full enough you might cast Hellraiser for cheaper. Second: you can use any non-creature spell and are not limited to instants. Therefore Hellraiser can be combined with more deckbuilding options.

This first version wants to play a couple of "fair" cards, which can discard themselves into the graveyard and are quite good hits for the hellraiser.

Advantage: We do not need discard outlets for the deck to work and we can still fill the graveyard during an opponents end step for example. Except for Magma Opus the deckbuilding cost for our expensive payoff cards is rather low (boon and shark typhoon cycle for another card early, etc).

Disadvantage: Getting a shark typhoon or a boon for free is powerful but might be too "fair", as it does not effect the board. Also it is more difficult to build a large graveyard for the cost reduction or Creativity x>1 without playing more dedicated discard, mill outlets.

Some card choices:

Dragon's fire: Most creativity decks run fire prophecy in that spot. I think rummaging hellraiser back into the deck is not that important for my build though. Dragon's fire can hit planeswalker instead and occasionally might deal 4 damage.

Draconic Intervention: This card is not very powerful by general consensus, but if any deck might be able to make it work its going to be the one playing a dragon, magma opus and boon. A "fair" version of Creativity Hellraiser probably is going to need a main deck boardwipe (and i like the exiling and big damage against mono green for example).