The next GB is the Fire GB and we need to make our way back to the Valley of
Flames where we picked up Salamando. Conveniently, the Valley of Flames is
just south of where we are right now. I don't recommend you go there just
yet. Just north of the Valley you'll find Deen. Land here, save and refresh
at the inn and restock up on supplies as you need. _NOW_ head for the Valley
of Flames as you did last time (northwest, west, west, southwest, south [if
you go southWEST instead, you'll see two merchant cats who will sell you
really good weapons and armour -- I recommend you consider buying some of
their stuff, but it's all very expensive], east, southeast.) Once inside, run
for the Gold Statue as you did before (south, south, down the steps, east,
south (down the steps), east, northeast, follow the path as it curls around
and exit west. Bear in mind that the enemies here are all around L30. You'll
find the Gold Statue below you. Save. Now, head up the steps and through the
opening in the north. Now follow the path south. Go northeast via the steps.
Go northeast again, up the steps, east, east, south (beat up the enemies
first), southeast (don't take the steps route), down the steps, east,
northeast (beat up the enemies first), southeast, southeast, east, northeast
and then prepare to face:

***Boss: God-Beast Xan Bie***

Xan Bie isn't too bad. He has several forms: flying fire (only hittable by
magic), normal fire, dragon fire and furnace healing. If you've got Duran or
Carlie on your team, make sure you cast Ice Saber on your team before you
attack. Since water puts out fire, use ice and water moves where possible. If
XB casts Flame Saber on any of your team, use the Stardust Herb or cancel it
with another Saber (preferably Ice.) Remember, if any of your team has been
Flame Sabered, you'll be HEALING Xan and not damaging him (it?) XB does have
several powerful spells up his sleeves (if he HAD sleeves, that is...)
Anyway, make sure you heal after he casts Gigaburn, Lava Wave or Heat Beam.
After you've taken him low enough, he'll retreat into the furnace and get
about 1000HPs back and be much stronger. Cast all stat-down spells again. You
_can_ take out the furnace so that XB can't heal (I recommend you do this as
soon as possible.) Once inside the furnace, XB will attack himself with Lava
Wave and Heat Beam, healing himself. This battle is shorter than Dangaard's
but in some cases it is more intense as spells end up flying all over the
place. I tend to use Angela's Ice Smash (multi) the most here. You can do
around 400HPs damage per go after casting Mind Up/Down + Ice Saber. I
recommend that you use any Water or Ice-based move like Ice Saber or Ice
Smash. If you do this, the fight won't last very long.

Once you've beaten Xan Bie, you'll end up outside the Valley of Flames, fully
healed. Make your way to Sultan or Deen to heal (the enemies here shouldn't
be too much of a handful by now.) In case you've forgotten, here's the bit
from earlier on. 

Now make your way back to Sultan by going west, northeast, northeast,
northeast. From here, you have two options. Either go to Sultan or stop off
at Deen for supplies. To get to Deen from here, go southeast, east,
southeast. Stock up, rest and then go west, northwest, west to get back to
here. If you want to go to Sultan direct, from this screen, go north, north,
west, northwest, northwest, west. In Sultan, stock up on supplies (if you
decided not to go to Deen) then sleep and save at the inn.

Whether you're at Deen or Sultan, stock up on supplies and save at the inn.
Then, when you're ready, call Flammie. Next stop, the Sub-Zero Ice Fields!