"An effective warlock must have either Destructive or Summoning magic. You don't have to get both as their function overlaps. Reaching Expert level and spells in either "the Red" (destructive) or "the Green" (summoning) in this mission is your top priority. Another skill that might boost your hero later is "the Yellow" - Light magic. Resurrection will make the Warlock campaign finale an one-sided massacre. Besides, all magic heroes should seriously consider "the Blue", Sorcery, for the quick and cheap spells of mass destruction."
Kudos to Robenhagen, Rapier, Infiltrator, Maltz and Psychobabble for sharing with us their knowledge of the game. I know I am a better player today thanks to them.
Map 2 - The Expansion
Size - Very Big
Level cap: 18
Carry Over: Raelag & Shadya
This mission is not difficult, but the next one (the Cultists) is one of the maps that most frequently results in cries for help, especially after patch 1.2. Therefore, your primary goal here is to build a powerful Raelag to pull through what's coming ahead.
Spoiler: view a screenshot of the surface
View a screenshot of the underground
From now to mission 4, Raelag will always start with a small army, but he is going to face rather powerful AI heroes and neutrals quite early. A might-oriented Raelag is not going to turn the tide, unless you lower the tide (via difficulty level) yourself.
An effective warlock must have either Destructive or Summoning magic. You don't have to get both as their function overlaps, and you can only cast one spell per turn. Reaching Expert level and spells in either "the Red" (destructive) or "the Green" (summoning) in this mission is your top priority. Another skill that might boost your hero later is "the Yellow" - Light magic. Resurrection helps tremendously in the next mission if you start with it, and it will also make the Warlock campaign finale an one-sided massacre. (You can learn lv 5 Light and Dark magics on this map only via the Dragon Utopia and the Mage Vault.) Besides, all magic heroes should seriously consider "the Blue", Sorcery, for the quick and cheap spells of mass destruction.
Prior to patch 1.3, Warlock's Luck does NOT affect Empowered spells, so the entire Luck skill was not very useful for a magic hero. However, patch 1.3 changed everything -- now it is fully possible to have Warlock's Luck triggered on top of Empowered spell. Warlock's damage output never went up this high before, and neither did their mana cost -- Patch 1.3 boosts high-level destructive magic's mana cost to almost 200%, and they slashed Meteor Shower to be exactly the same power as Fireball, just bigger in area!!
Starting bonus: The minotaurs gives you more confidence to rush out early.
The picture on the right is a sample Raelag build on patch 1.3. Enlightenment would be very helpful to increase Raelag's mana count for the insane mana cost now. However, Light (Resurrection) helped me so much in the later missions.
Before you do anything, if your Raelag does not know Meteor Shower yet, you should make it happen now. If your level 4 magic guild offers Chain Lightning, you can easily restart the mission and try again. If you opt for the Summoning route, then you really need Summon Elementals.
Your starting area is on the NW of the underground portion, with a nicely-built town. There are three more dungeon towns out there, all underground and controlled by the orange player. The closet town is to your east. You can reach there only through the paved road on the ground level.
You can either make a counter-clockwise circle to flag various mines first, or directly rush out with the stairway in the middle (green A). Flagging mines does not make a big difference as your town is well-built already, but it might give your Raelag a few more levels, to obtain some useful feats so it is worth the delay.
A nice battle trick for a powerful warlock like Raelag is to deploy only Deep Hydras. Keep them waiting to give them more turns to regenerate lost HP. These creatures soak up a huge amount of damage, which should give you enough time to wipe out the neutrals. While fighting slower enemies, you can deploy only the blood furies, and let them run back and forth on the battlefield, so Raelag can pick the creatures out slowly to conserve mana.
In the middle of your HQ is a Seer's Hut (1). Visiting this hut triggers the mission of brining the Tear of Asha back to your starting town, and building the corresponding structure. Throughout the map you will find a total of six obelisks, each revealing a small portion of the map. This quest is the last step of this mission, and your priority now is to take care of the orange player.
Just NE of the hut is a Tan tent. Throughout the patches (as of patch 1.3) this tent does NOT match the only gate (Red) offered on this map, so you will never be able to pass the gate even if you have obtained the key from this tent. Fortunately, there is nothing important beyond the gate; just you get an idea of how insightful Nival is.
The (A) stairway takes you to ground level. You will see a two-way portal nearby, which leads you to an obelisk (yellow O1) in the east. You don't have to visit it now as you will need to visit several more to point you to the Tear.
You have a choice of route here. It is faster to go east, and turn south. The mana well at the intersection is very useful, as you can summon creatures from down below. Defeat the garrison (2) to the south (no unit loss for a Hydra-only army), and keep going on the paved road. You will pass a witch hut on the side, and eventually hit an intersection with a stable (3).
Sooner or later you will encounter orange heroes. If you have a Destructively oriented Raelag, your units are just there to soak up a few hits. At (3), turn north and rush towards the stairway (B). You will soon see the first orange dungeon town. It is yours now!
Once you take the first orange town, a few things happen. First, you will be joined by a female Dungeon hero, Shadya, in your starting town at the beginning of the following turn. You might suspect she is actually someone with Agrael... anyways, Shadya's real identity will be revealed in the last (Wizard) campaign. If you haven't flagged the mines surrounding your starting town, Shadya can do that for you now. Shadya suffers from low spellpower and a rather-useless special ability, so she needs an army more than Raelag. You can send Shadya out to exchange armies with Raelag whenever convenient.
Shadya is going to stay with you all the way to the last Warlock mission and show up briefly in the last campaign, so it is beneficial to train her to help Raelag. Even though Shadya says she is good at assassination and some other dirty works, she always comes with Destructive, Dark and Defense. Sorcery is a no-brainer, and the last slot is up to you. If you are playing on patch 1.3, you can go for Warlock's Luck.
A second change is that the orange AI is alerted by the loss of their first town, and will now attempt to send out "messengers". The messengers are essentially their current and future heroes, who will try to make a run to the north edge of the map, through the intersection (3) and the garrison (2). Sometimes, they take the west route at the intersection. Each escape of these "messengers" means the permenant disappearance of themselves, but they will bring in a moderately-powerful yellow army at (4).
A third change is that somehow the next AI town (the middle-west one) will be fully built in a very short time, probably instantly. On patch 1.3 heroic, I noticed that the AI is becoming very good at building towns - so all of them are fully built when I paid a visit (and I didn't take longer than in the previous patches).
So you face a dilemma here. Do you take care of the messengers, or take the next town first? Don't forget that you have Shadya to share the work. You can dump all good armies to her, so she can take care of the messengers for you. Your Raelag should be able to take towns with very little loss now.
With time, you will eventually take all three orange towns, and defeat the yellow heroes, if any. You can then take your time to tour the map and pick up various stat bonuses. Stairway (E) takes you to a Dragon Utopia (5) underground. By defeating the guardians you can learn some level 5 spells if you are eligible (having Expert level on the magic skill). For example, my Raelag in the above picture learned Resurrection and Word of Light from the Dragon Utopia, and Shadya in the picture learned Puppet Master and Curse of Netherwind from the Mage Vault. These buildings also refresh themselves every few months, so as long as you reached Expert proficiency, you can eventually learn all the lv 5 spells.
I have marked the locations of all six obelisks (O1-O6) on the map. One of them requires you to travel underground (stairway F), and the other requires you to defeat a SW garrison (6). You can rescue an interesting Necro hero from the prison nearby. After revealing enough maps, you should be able to make a good guess of where the Tear is by planning long hero trails, and check whether the planned trail is on your puzzle map. If the trail shows up on the puzzle map, then you have narrowed your search area. Dig up the treasure and take it home, and you win this mission!
If you have serious trouble figuring out where the tear is, I've marked Red X on the locations where I found my tears, during my 4 runs of this mission.