There will never be a difference in HQ-rate between a 98 and 99 synth as you can never break a tier on them. And dunno about Hades but on diablos NQ is 80-90k loss . . . wich is significant nowadays.
The recipe stated below is false. Using a Guivre's Skull, the recipe is Bonecraft(98), thus giving a slightly higher chance of creating a Hiqh Quality Wyvern Helm.
With a regular Wyvern Skull, the recipe is Bonecraft(99) and thus a slightly less likely to become a High Quality Wyvern Helm.
If you happen to obtain Guivre's Skull, it's always worth it try to get a High Quality helm. If it becomes Normal Quality, you'd have lost only a small amount of gil.
