1) Ideas Unbound is an interesting idea. The main issue I see with it is that in Modern Treasure Cruise is clearly the best draw engine (with Dig a close second) whereas Vintage has many more options (Gush, Jace, Ancestral, Library). You can mitigate the inherent card disadvantage of Ideas Unbound better in Modern, but in Vintage your opponent is more likely to outdraw you and if they counter the follow up Cruise it can put you in an insurmountable hole. I do think is worth testing though as looting has become so much more powerful with dredge. I have also beat leyline of the void and rest in peace with the deck as Jeskai Ascendancy can pull off a super Glorious Anthem impersonation with Pyromancer tokens. The quality of the draw spells in Vintage makes the deck less dependent on Treasure Cruise in such situations.
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2) Izzet Charm is similar to what The White Dragon was saying with Ideas Unbound - the looting is insane with Treasure Cruise and I find all of the modes relevant during games. Three might be too many and two is probably a better number. I started out at 1 and kept on increasing them. It helps fuel your first Treasure Cruise and after that helps to Chain Cruises together by discarding the excess lands. I have been really impressed by it.
3) Green splash with grudges has been discussed as part of the more creature centric build. The issue I have is you primarily want it against Shops and it can open you up to wasteland. I generally want to fetch a basic Island against shops, but then following with Tropical Island would mean I need 4 lands/Moxen total to cast Ascendancy. Though, I suppose you could view it as more of a bonus with a singleton Trop to fetch when relevant. Or get more creative with duals and throw in Taiga/Savannah. It's a good idea.
4) Dack is pretty good in my experience. I had actually been siding out Fatestichers and trying to win by killing most of my opponents threats while just burying them in card advantage. It's actually worked against shops a couple of times and Dack facilitates this plan (plus they tend to name Fatesticher with Revoker and not Dack). Problem is that it's hard to get testing in agains Shops online because of how underrepresented it is so this has been based on relatively small sample size. Thanks for the comments. I'm glad to see that you are back playing in tournaments on MODO, Coopes.
There are a few points to make here:
1) IU has proven very solid in my testing (albeit mostly modern) and I don't mind casting it pre- or post-ascendancy. It digs and sculpts even without the bonus of fueling cruise (though it does add +4 to the grave on turn 2). Pitching fatestitchers is what you want to be doing anyway, so it helps there, cruise aside. It might just be outclassed in vintage, but it's another option. I think it is second only to cruise in a Modern ascendancy deck.
2) Izzet is similar to what IU does as far as feeding cruise, but it is VASTLY inferior when going off or for sculpting in general. On an empty hand, you can just ancestral, play out the 3, and discard nothing (or just what is left like a stitcher/extra lands). Post-ascendancy, it's not even a contest how much better IU is. You are basically running 4x UU costed ancestrals, not filtering. I find that ascendancy can crap out at times if you draw multiple creatures/lands, and with izzet you sometimes have to pitch cantrips. IU is straight draw 3 in this case. I have found the shock to be somewhat relevant. The filter is also relevant. But I have found the spell pierce often irrelevant or uncastable. It's biggest use as a counter is pushing through Jeskai, and that would cost 5 mana which is unlikely. Decay or leylines or 1 drop answers are more common than anything a 2 mana counter can stop. I actually run a few pierce since the 1 mana difference is the grand canyon in practice many games.
3) I think in vintage green is unnecessary. In modern, I've found it to be mandatory. In vintage, you have moxen and such to play fast and have FoW to stop spheres and such. In modern, there's none of that. The deck really CAN'T go off before turn 4 in modern unless you run mana dorks. Mana dorks also dodge the grave hate. I have found pyromancers to be decent in the vintage version, but crap in the modern version. In modern, it's a weaker version of delver, and as you are "going off" to churn out tokens, they don't have haste and you will most likely win with stitchers/birds anyway. Glittering wish is also huge. You flat out need it in modern since you have no black tutors or ET. On that note, ET could be a very good inclusion in Vintage to stay 3 color. It gets you JA, lotus, or other, and with all the cantrips, it's as good as a DT that costs UW (or just W and -2 with probe). To fight shops, hurkylls is by far the best answer. You can't really win picking off one artifact at a time. You need to do the storm approach and EoT sweep, then win. I don't think the vulnerability to wastes by adding green offsets the bonus of grudge. Hurkylls > Green.
4) Dack is neat, but expensive. Very hard to cast in an already mana-light deck, and sorcery speed. As I said, I think hurkylls is the real answer vs shops. That said, it's not at all a bad card and could fit just fine. I think the chewers are good in general, but maybe not best in this deck since they don't trigger ascendancy and don't solve the multiple-lock-piece problem. And though shops is not an issue in modern, I've found 4x trinisphere to be an excellent trump to the deck in Modern. A turn 2 trini is almost always GG vs JA in modern.
Sorry to mix modern into vintage, but this deck really crosses formats and I think there's value in seeing what works or doesn't in all the formats here. The same can't be said for most decks, but JA is a unique beast.
