Gothic/Xardas the Necromancer

Talk to Saturas. He will explain that there was a forgotten 13th sorcerer who helped create the barrier, but he fell out with the other mages when he dabbled in necromancy. The only specifics you are told is that his tower is somewhere in the Orc Lands.

First, if you were a member of the Old Camp you can now join the New Camp. Join the Magicians of Water if you were a Magician of Fire, or the Mercenaries if you were a Guard.

To join the mercenaries, talk to Lee on the dam. He tells you his story and gives you the Mercenary's Armor (Weapons 55 Arrows 10 Fire 25) and can also sell you the Heavy Mercenary's Armor (Weapons 55 Arrows 10 Fire 25) for 2100 Ore. If you have the Ore, be sure to buy it.

If you joined the Magicians of Water you get a free Water Robe (Weapons 65 Arrows 5 Fire 40 Magic 15). Again, 2100 Ore will get you a Heavy Robe of Water (Weapons 70 Arrows 10 Fire 45 Magic 20). Be sure to buy it.

Before you leave stop by Cronos. If you're a mage, buy whatever rings and runes he has that you want. If you're not a mage, grab at least 10 scrolls of Ice Bolt and another 10 of Fire Bolt. These are required to pass an upcoming challenge, and you'll just have to come all the way back if you don't have them or run out. Also, you must have a hammer weapon of some sort. Go buy or find one if you don't have one already.

Make your way into the Orc Lands. The easiest way is to take the gateway near the Old Camp—however the two guards there will attack you on sight, just like all other Old Campers. There will be more and more Orcs the deeper you go, but eventually you'll see a forbidding tower in the distance. Skirt around the edge until you find a narrow path.

Equip the best hammer you have and head onwards. Kill the Stone Golem with it and grab its heart. Equip your Fire Bolts. Kill the Ice Golem and grab its heart and fragment. Equip your Ice Bolts. Kill the Fire Golem and grab its heart.

Head on into the tower. Here you'll meet a Lesser Demon that demands a test of faith. Since you've already done that just give it the hearts and it gives you a rune. Use the rune to reach an upper level. Once there climb the ladder and talk with Xardas.

Xardas talks with you about all that has transpired and that the Water Mages' plan to detonate the Barrier is not the solution. He tells you about The Banished Orc Shaman who is crucial to finding the Sleeper and putting him to sleep for good.