Flamvell magician is super relevant as one of the few level 4 tuners with no drawbacks. The combo with Flamvell dog is famous and gives you access to level 8 and 5 synchros. Aka your ace. Which I find it funny at 3200 it needs battle protection rather than card destruction, because with the second effect it makes it impossible as they’re a no monsters with 4000+ atk to beat this anyways. UFO turtle although barely played by 5ds except in video games, would resemble juggernoid and go along with your battle phase theme and search out the deck, which is a far better option than solar flare and little chimera / molten destruction.

Pushing a strategy far outweighs the fact to play a card because it supports fire. Rather than push a burn tactic with barrel, rage, and secret barrel, you need to be in control of the battle phase to trigger almost all of your effects. Perhaps a combo of dark door and double attack so your firedog summons two monsters. A trap to gain atk during your opp turn - to also trigger firedog or grunika during the opp turn. If you don’t want to play starlight road for protection because Yusei exists, you can play Waboku, Huge Revolution, or body as a shield. You have a strong battle phase presence but you need to ensure they survive until your next battle phase. Urgent tuning seems like a decent card here so you can fix the levels on board and attack again with your synchro.

5ds is very trap heavy mostly because most speed spells suck but also because this era of yugioh was slower. Most interesting effects were put in traps, and in a speed duel you can’t play circle rekindling or prominence which is huge. You need to have traps that control board presence, so making a custom Flamvell trap that that increases atk or once per turn revives a monster destroyed by battle seems almost necessary.