Does Seraphynx' third ability prevent the FoV charge from setting you on fire? Can somebody test this?
Seraphynx - Fang of Vog
What about Drakon? Does his defense buff help a lot with protecting you from the FoV charge?
Probably not. I wish I never chose the drakon, IMO it's useless.
Now I don't own a dragon , but if you wait a bit once you get to his ultimates, then he will be very useful. You just got to be patient.
Defence and resistance are separate matters so no. Sadly, there's no page on resistance so I'll explain here: resistance is the thingy you have that protects you against status effects. It's entirely separate from defence and is unaffected by Drakon's Flame Barrier.
Shouldn't it at least reduce the damage you take from the fire?
Does it boost your defense that's already there or does it just reduce all incoming damage by a certain amount?
No. The damage you take from fire is reduced by fire resistance. It boost the defence you already have by I think it was 75%. Therefore, it'll be the most useful with powerful armour. Keep in mind that it'll still hurt to take damage, though. Ideally, you'll pick up a defence orb and drop some Venom Veilers if you ever plan on using Flame Barrier to tank.
Been there done that and no it doesn't. But the heart drop increase can help heal off damage plus the shield allows you to get up close and personal with big monsters (like the Jelly king) so you can unleash a (relatively) safe charge attack.