Now, I know what you're probably thinking: "Why is this idiot not running tract, lurrie"? Well, I do have legitimate reasons for not running them as well as a few other things, which is the first thing I'll go into.
1 - More Fiendsmith engine (Tract, Lurrie, Sanct, Necroquip Wave High)
Obviously given that this is a Fiendsmith deck instead of a Fire King deck, you would expect it to be running all of these staples of the Fiendsmith engine, right? However, there is one important detail that heavily influences my decision: Almost nobody is running Nib this format. Wave High is certainly a very good card, but it's main use is undeniably to stop Nibiru. But unfortunately, Silvia has taken his job from him and so now Nibiru is suddenly a lot less useful. And you would be right to think that having 2 ways to stop Nib isn't inherently bad, but the thing that I'm really getting at is that there are so many ways to stop Nib now that running it would be a liability, therefore I don't see much use in running Wave High anymore, or Necroquip by proxy.
And you might think that's also the entire reason I'm not running Lurrie/Tract/Sanct, but you'd actually be wrong, because there's a whole other reason, and it's that they're basically useless. You can make Wave High on top of the current board by just drawing Lacrima or Engraver and tributing/sending them to use the main Azamina combo if you run Agnumday (which I'll get into later, don't worry). AND, on top of that, the Wave High turbo combo makes Wave High as the 6 summon, so if you do that first than you lose a negate because they'll just Nib after you summon Engraver, and the 2nd negate from Wave High is now gone.
2 - Knightmare Phoenix
I will admit, I have a bit of a grudge with this card. I just don't think it's very helpful a lot of the time, but even I can't deny that it's a good card which is worth running.
3 - Kashtira engine
Mid as hell tbh
Now that I've gotten that out of the way, it's time for the fun part: The cards that I AM using, when any sane person would say not to.
1 - Morrian
To get the elephant in the room out of the way, there are a couple reasons behind running Morrian. First off, it's the best card to search with Silvia (I bet you forgot it could do that, didn't you?) and in case you were wondering, yes it does come up, but I will admit that a lot of the times it comes up are going 2nd against another Snake-Eye deck, because 99% of players will use Princess on Silvia right when they get the chance. The 2nd reason is the 2nd effect, because that means it's essentially a free discard to summon Diabellstar since you can get it right back after summoning an Azamina monster, and this card specifically is a very good option for mitigating that cost because of interactions with Debtors that I'll get into later. But as for that 1st effect... it really is quite mediocre, huh?
2 - Subversion
First off, if your starter is Diabellstar (not Seeker) then Poplar has nothing to add when you summon it with Flamberge turn 2, so running another Snake-Eye spell is definitely a good idea. But as for Subversion specifically, it's actually a surprisingly good board breaker, both to draw and to search. And to remind you, it can be searched not only by Poplar, but also by Diabellstar, Rcielago and... well, Rcielago because it's also a Sinful Spoils. You'd really be surprised by how good a very searchable 1 for 1 trade actually is going 2nd, and it's also a good thing to add going 1st if you have extras, because the other option would be something like another Seeker.
3 - Agnumday
You might think that running Agnumday when I have so little of the rest of the Fiendsmith engine is contradictory, but actually it isn't. If you go through the main Azamina combo that uses 2 discards (which you have to go through if you opened Deception and no other combo), you end up with 2 extra pieces of material and Agnumday is unironically the best thing to use one of them for (the other free material isn't used, in case you were wondering). You can just use a Snake-Eye that you summoned with Flamberge + Sequence to make it, then you just link it away anyways. To be specific about it, the point of Agnumday is that on turn 2 if your opponent outs Desirae, you can use Lacrima to summon Agnumday and then use Agnumday to summon Desirae.
Obviously going into Agnumday isn't always worth it, but if you go first and you draw something like Seeker + Fuwalos + Fuwalos, then you might as well, huh?
4 - Dominus Impulse (x2)
The idea behind Impulse is that going 2nd, you can side out Lacrima and Engraver for it. The only things it stops in this deck are Fuwalos and the Fiendsmith engine, so you can just shotgun any Fuwalosses and not go into the Fiendsmith engine, and lets be honest here how often do you go into Desirae going 2nd? You could run something like Nib instead, but that's a lot of risk when this deck doesn't even have 3 Imperm.
5 - Debtors (x2)
The main reason to run Debtors is to stop Impulse, but it also has a very good use in recycling Silvia on turn 1. It's pretty simple to see the application in chaining Debtors to an Impulse that's chaining to your Hallowed, but Debtors can do so much more than that. For example, the simple way you can use it to recycle Silvia is to send it with Diabellstar and then use the 2nd effect to summon her back. But, the other thing you can do is, instead of using the Hallowed 2nd effect to put back Rcielago then using it to make Silvia, you can use the Debtors to make it instead. Then, if you have to use Silvia on turn 1, you can then use the Hallowed 2nd effect to put back Silvia and use it with a Sinful Spoils in your hand (something like Morrian or Subversion) to get her back, AND you'll also still have the Debtors in GY to get Silvia back on turn 3. Alternitavely, you could just run a 2nd Silvia and then you wouldn't need the Sinful Spoils in hand, and could just use Deception on the opponent's turn.
6 - Goddess
WHITE WOMAN JUMPSCARE!