Purge | Mission 2: The Call of Malassa - main quests Heroes VI - Shades of Darkness Guide
Last update: 11 May 2016
Objective: defeat the Soulscar and Inferno armies
Reward: 40000 EXP, +3 leadership
From now on, you can recruit Shadow Dragons at your city. Additionally the ice barrier blocking access to the surface has disappeared (M2, 2) and all the gates which were separating the Elven groups have opened (M1, 11). These changes let the enemy attack you from multiple directions: you need to act fast and block the enemy from making a move. Additionally, two further side missions will activate in the nearest turns: "Independent Forces" and "Whispers of the Faceless". I'd recommend firstly taking care of the enemies and exploring the map by the end of the mission.
After buying units at the city you should head south while visiting every location on your way. Your first destination is the Inferno fraction city (M1, 12): conquering it will cut the enemy from a big portion of the map. You should place an Improved Town Portal in both the first city as well as in the newly obtained one. It will let Raelag defend both location in case of an attack (just use the Basic Town Portal or Improved Town Portal spells, depending on your hero's location).
Your next destination is on the surface - the city at (M2, 3). Just like with the Inferno city, place an Improved Town Portal and visit all the observatories in the area (M2, 4) which will let you see an incoming enemy and teleport one of your heroes to lead the defense of the city.
Once you have those areas under your control, you can head to the northern part of the caves and obtain all the mines and the local fort found there (M3, 23). Now you just need to attack the last city of the dark elves (M1, 13). If you haven't yet finished the side missions, you can leave one of your heroes here together with half of your army (just standing one field from the city gates will prevent the enemy from heading out) and take the second one to finish exploring the map.