[Deck] Dragon Stompy

[QQQ]

I've always been inclined to cut 3spheres versus control because the game inevitably gets to a point where it isn't relevant.

Historically I agree. However Snapcaster is effectively neutered by 3Sphere. Without bringing in GY hate. That, in addition to it's blowout potential and protection against countermagic(as always) is why I like only against the 4 Snap matchups with decks that are optimized to abuse him.

I'd also argue that Blood Moons are stronger than Maguses because there are less ways to remove them.

Obviously that's true. But Moon can be pretty weak in general against this deck. And they don't have real blockers, so every threat is relevant. Magus also turns off all their removal. Yes, they can float and kill. But they can do the same vs Moon. The odds that they have open mana and the removal spell are far higher for Magus. But to me that's outweighed by the threat itself, and additional threats for each other Magus where redundant Moons are dead.

I'd be interested to hear more about the Phoenixes. in the casting cost isn't the worst, but I'm curious if Pia Nalaar wouldn't serve you about as well.
Pia gives you a few additional tricks against Batterskull/Jitte (sac the token after blocks) even though you only get to do it once.

I don't have much more at the moment on Phoenix. It's my substitute for Copter. Which I see you can fit without 3Sphere hurting your Red. Not being able to cast Mox T1 is absolutely crippling, which led to the change. Otherwise, with the 6 token producers I was very happy with 2 Copter. I will say that I have been sorely disappointed in Pia every time drew and/or cast them. To me it's the most overrated card in the deck just above Prodder.

Have you tried 4 Chandras main? I strongly encourage you to try that if you haven't.

Yes. Not only is Grixis Delver the most popular deck generally, it's even more so around me. And it's the one version that Chandra is just bad against. YP, TNN, Gurmag, Bolt, etc. That's the vast majority of the reason. That is actually the reason for my main inclusion of 3Sphere. Though we're not just talking Grixis there. Against Delver, every lock piece you drop in the first three turns greatly improves your chance of winning. Whether it resolves or not. If they Daze your Chalice, they're not dropping YP next turn. If they Force your Moon, they don't get to use that Brainstorm to find Bolt for your Magus. And so on. So when you start dropping real threats, they are out of answers.

Here's what I'm trying out currently. With the same caveat as you:

4 Hanweir Watchkeep
3 Qal Sisma Behemoth
3 Smuggler's Copter
4 Magus of the Moon
4 Simian Spirit Guide

4 Bonfire of the Damned (although I'm thinking Rolling Earthquake is probably better)
4 Fiery Confluence

4 Chalice of the Void
4 Blood Moon
4 Chandra, Torch of Defiance

4 Chrome Mox
10 Mountain
4 Ancient Tomb
4 City of Traitors

My sideboard would contain 4 Trinisphere and the rest I'm still working out.
The idea is to keep the opponent's board clear with Confluence and Bonfire/Earthquake and make my threats difficult to kill through conventional burn (bolt or P Fire) which is playable through Moon.

I haven't played Watchkeep. I found 3 Copter was too many with 6 token producers, and you have none. That would concern me. especially since you want to be actually swinging with all your creatures but Magus. I found the self damage from Earthquake added up too quickly with the deck's inherent self damage against the decks you want Earthquake against. But that was in limited testing. I did test Behemoth, and found that having to pay was a nuisance late, but made the card almost unplayable early. It's not bad, but it causes sort of an inconsistency in a deck that can ill-afford it.