Gor Gammar is a massive Orc city the farthest down south. The land is very arid and has lava pits in certain areas. The sky is also red. Also located in Gor Gammar is a necromancer settlement. Many strong necromancer spells are sold by the necromancers there. This place is very hard to find so search everywhere if you want to find it. Section 20 on the map is Gor Gammar.
All around the castle are Lava Dragons. Inside are orcs all over the city with bows and strong weapons. The orcs in Gor Gammar have a lot of strength. The way to get in Gor Gammar is to go around the city and go into a Cave entrance and come out the other way into Gor Gammar. Also Inside Gor Gammar is the Fire Element needed with the Relic Frame.
You will immediately be swarmed by orcs, but if you are doing the quest to get the Fire Stone, then a necromancer will give you a bomb which can destroy everything in Gor Gammar instantly.
Another Way to get into the city is by equipping the Orc Camouflage armour. This will be much easier, but you don't get the experience and/or satisfaction for blowing the city up with a massive bomb.
The Fire Stone itself is in the Centre of the City (What a surprise!). If you want to try a challenge, try getting the Fire Stone without using the Camouflage or the Bomb.
To get the Bomb, you will need to speak to the Necromancer Ashmohar. He is situated quite a long way North-East, in and area just below the Drak'ar Desert. He wants you to bring him a scorpion tail. When you give it to him he wants you to get rid of a group of octagons who disturb the glade that he wants to use for his research.
After this, head to the glade and he will give you the bomb. If you return to Ashmohar after you have detonated the bomb, you will find a paladin who has disposed of Ashmohar. To get the Camouflage Armour, you will need to do a quest which is given to you in Cathalon.