If we look at Death Phoenix itself, it has to be somewhat decent right? A 4 mana creature with 9000 power, as well as having the same effect as Bolmeteus, and being a Lost Soul when leaving the battle zone. No doubt that its a great card once it hits the field. It might not be on the same level as its vortex evolution brother Wise Starnoid, but there should be a way to make it atleast work to some degree. But there is a couple of big issues here:
The card requires a zombie dragon as bait, as well as the fire bird to evolve. This is the real problem, as we really dont have many good zombie dragons in tcg. There is Giland and Jagraveen, and all the others are just bad. Giland is fine despite its suicidal effect. Its cheap and can double break if it has to. Jagraveen is kind of like a large Bloody Squito, that can also Double Break. But the fact that it costs 2 more mana than Death Phoenix, makes it kind of slow as evo bait.
For the fire bird baits it is a lot easier. A playset of Gigappi Ponto and Kooc Pollon is about what you need. You could also add Cocco Lupia and/or Totto Pipicchi depending on your build.
So despite these flaws, i do see potential in Death Phoenix itself. The bait it requires doesn't exactly produce the most consistent decks, and i kind of feel like you need to add water to get that extra defense, draw power and consistency that you need for the deck to have a chance. These decks have very little defensive capabilities as well, so im thinking about Miraculous Meltdown as well, as a backup plan for the deck. I still havent come up with a final build, but im testing as we speak. But maybe im thinking in the wrong direction. Maybe a FDW control deck is a better build for Death Phoenix, with less focus on the bait, and more focus on draw power and setup. I was thinking it would be best to go all out with the bait, and try to summon Death Phoenix as quick as possible. But maybe im wrong. If any of you have had any success with this card, i would love to see some decklists. I will continue to test out different builds, and i will be sure to make a post and let you guys know, if i manage to come up with something that works!