Gothic/The temple of the Sleeper

This is it, the endgame. First, some unfinished business.

The Old Camp
Use the Teleport to Magicians of Fire rune to access the Old Camp (you could also use a Transform into Meatbug scroll and crawl under either gate, but the rune is quicker). Wherever you go in the Old Camp every guard or shadow will attack you on sight and your armor is no match for dozens of crossbow bolts, so you may want to get in and out as efficiently as possible.

If you chose to be a Meatbug, remain as a Meatbug until you reach Gomez's castle, as the guards won't attack you in this form. If you chose the rune you'll arrive in the middle of a group of guards headed by Barthalo. You'll learn from him that they've locked up Stone the blacksmith. It shouldn't be difficult taking them out. There are more guards in the rooms downstairs. Either way, once inside the ore baron's castle you need to take Gomez out. First deal with Scar and his friend. If you take the door furthest from the throne and entice them towards you Gomez should remain seated until you're done with them.

Once they're dead (and Raven too, if you didn't get him already) confront Gomez. His sword deals massive amounts of damage, so heal up first and be sure to combo him repeatedly so he doesn't have a chance of killing you. Once he's dead grab his key. Head upstairs and go into his bedroom (or backup throne room, or whatever) and loot the chests for some permanent stat-boosting potions.

Now head to the smithy. Clean it out, because you'll be needing it to be safe for what's coming up next. Once you've dealt with most or all of the guards inside the castle head into the guardhouse, then go downstairs to the dungeons. Here you'll find Bullit playing sentry (if you didn't kill him already) as well as a guard or two. Keep going and open all the cells until you find Stone. Talk to him and tell him you're not with Gomez and he'll head on back to the smithy.

Follow Stone back to the smithy and talk to him. Be careful drawing weapons around him as he'll threaten you (this is why it's best to deal with the guards there ahead of time). Once he's back in front of his forge he'll offer to make you a variety of things. He offers to make some rings, but anything he makes can be purchased in the other two camps or found as loot, and you'll likely have the best enchantments by now anyway. Instead ask him to reinforce your armor. After a brief moment he does so. Put on the Improved Ore Armor (Weapons 100 Arrows 30 Fire 45 Magic 15) and teleport back to Xardas. From there make your way to the temple once more to take out the fifth and last of the heartless shamans.