So first thing's first, apologies for the lack of a response. I'm not on here nearly as much as I used to be so I try to let others offer some feedback when possible.
That being said, could you give us some thoughts about the level of competition you're looking to take this to? You listed the format which is a great start, but are you looking to take this to have fun at FNM or are you looking to be competitive/win FNM consistently (or even potentially enter in to higher level events)? This will help determine whether we need to be suggesting ways to take you deck toward a tier-1 status (and likely costing a fair bit more), or just making more general suggestions toward being a decent casual deck.
That being said, it's an interesting concept, but I don't know that it really will stand up to the rest of the field out there. For example, what is the plan against a control deck that doesn't really have creatures? Sure, you can pressure them with your board, but I don't know that it gets there against their removal suite.
Other thoughts:
- If you have the 4x Den Protector that you have listed in the SB, there's literally zero reason not to run them main. They offer an evasive beat-stick while also giving you the versatility to get the Deathmists and other cards back.
- Ire Shaman is outclassed by Abbot of Kheral Keep. But it would've been easy enough to overlook that one with Origins just hitting.
- I think you want more ways to interact with their side of the board. I'm thinking Exquisite Firecraft makes sense.
- I don't know that I'm really following your SB options, but perhaps you could give some more input on your thinking for them
- 59700999's suggestion for Shaman of the Great Hunt isn't bad. I would actually suggest a slightly different option, Shaman of Forgotten Ways would be decent in the SB as an anti-control card. You get to formidable and then use its ability against their open board.
- Gaea's Revenge is another good option to look into.
Questions:
- Generally speaking, what's your plan against something like Dragonlord Atarka?
- How do you deal with opposing planeswalkers?
I hope some of this is helpful. Remember, the more you can tell us, the more likely it is that someone can give you useful feedback.