Here is your starting location. Don't be scared of the shroud. The orcs will only attack from the north. So move all of your units north.
|Into the swamps we go.|
There are two mines on your side of the river. The closest one is to the southeast. You shouldn't need more than two mines to complete the mission.
|Here's the closest mine.|
|Guard the town with your starting units.|
As you explore north, you may want to move your units to the bridge.
|Prepare for the inevitable poison cloud attacks.|
Meanwhile, when building your town, you'll want to make sure you leave a lot of open space between your buildings. The reason for this is to avoid taking too much damage from poison cloud attacks.
You get two new spells in this mission: invisibility and rain of fire. Used together, you'll be able to do a lot of damage to orc units. However, learning both spells and training the units necessary to use the spell is very expensive. You certainly don't need to research these spells to complete the mission.
|The poison cloud attacks may come from across the river.|
Here's the first poison cloud attack. The warlocks come in packs and will blast your northern-most building. Occasionally, they'll target your units. It's important to immediately move all units away from the cloud and redirect any units who might walk through it. Better yet, kill the warlocks before they get close to your base. The poison cloud lingers for a while and will severely damage your buildings, but you don't need to repair anything until the buildings are in the red.
Thankfully there's a bug that causes the warlocks to cast poison cloud over the river from time to time.
|Guard the bridge.|
As you hold the bridge, set up the standard archer trap. However, be vigilant and use the knights to destroy orc catapults before they tear apart your garrison.
|The lower base is revealed.|
Use far-seeing to uncover the orc bases. There's one to the south and one to the north. It's easier to attack the southern base first because there are less defenders. Also, with the southern base destroyed, you have the security of a third gold mine should you run low on funds.
|Cast rain of fire to weaken the orcs (who cannot heal).|
While optional, you can use the rain of fire attack to soften up the orc defenses. Then, mop up with knights. Keep a few clerics on standby to heal the knights.
|Hit and run tactics are very effective.|
If your conjurer gets harassed, summon scorpions and run. Keep your clerics and conjurers away from the town. The AI has a tendency to attack buildings, depleting your mana. In fact, once the main defenders are killed, just pull your spell casters back and return them to your town.
|Crush the upper base.|
Once the lower base is destroyed, move your units to the bridge directly south of the northern orc base. Set up your archer trap at the bridge. Now, you have many different options to destroy this base. I personally like to summon scorpions and harass the defenders. Remember that the orcs can't heal their units. So you can soften them up with scorpions first and then move in with your knights.