The good option is to get back to the main corridor and as a matter of fact, your enemies will be hit by those fireballs #1. You can use this tactic during some other fights. Few moments later you will have to fight with another enemies #2.
You don't have to examine the north room. Go west #1 (M11B, 4). After a while you will get to the next room full of some crystal spiders. Do not forget about fireballs #2.
Choose the tunnel leading north-west #1. Turn right and choose the corridor leading north-east #2 (M11B, 5). When you will be the look for the chest (M11B, 6), open it and take the key.
Now you can return to the corridor leading north-west. Use the key to open the gate #1 (M11B, 7). Watch out for the ice golem in the next room #2.
Now go upstairs, but before you will enter the cave #1 (M11B, 8) save the game. Use all defensive mixtures and spells - you have to prepare for a very difficult fight. When you will try to enter the cave a short cut scene will start #2. After the conversation you will have to fight with two Ahn'Baels and three crystal spiders.
Rewards: Ahn'Bael, 225 EXP for each mine crawler worker, 244 for each mine crawler warrior, 35 EXP for each cave crawler, 311 EXP for each ice golem, 287 EXP for each skeleton, 287 EXP for each crystal spider, 750 EXP for the Minecrawler Queen.
Quest giver: automatically after speaking with Ixidia [The Lost Temple]
Description: This battle (M11B, 8) I advise you to start from eliminating all crystal spiders #1 #2. It is good to use some AOE spells here. Ahn'Bael sisters will attack you at once so kill all adds as fast as it is possible.
Now attack Ixidia #1 because she is weaker than the second Ahn'Bael. The good idea is to fight with the in a short distance. The flying monster should be killed as last #2. This will be a longer fight.
Rewards: The Divine Forge, 2050 EXP, 287 EXP for each crystal spider, 96 EXP for Ixidia.
The Divine Forge
Quest giver: automatically after killing both Ahn'Bael and crystal spiders [The Lost Temple - Xeshya's Grave]
Description: Use the passage leading upstairs #1 (M11B, 9) and after a while you will find yourself in the forge #2 (M11B, 10).
Go downstairs, watch the cut scene and explore the forge. It is good to collect all valuable recourses located here: red ore, magical ore and the holy essence #1. Open all chests and find the Divine Hammer #2 (M11B, 11).
Rewards: Thorniara, Divine Hammer, 6500 EXP.