Your relatively safe quarter consists of 1 town and 2 forts. There are three hostile factions: Inferno (1 town + 2 forts), Stronghold (2 towns + 1 fort), and Necropolis (2 town + 3 forts). They all launch sizable invasion to your land whenever possible. There is also a friendly Necropolis faction (1 town) which you can incorporate.
How do you deal with enemies 4 times of your strength? The loading screen gives a good hint: "when you are surrounded by enemies, finish them off one by one." This is exactly what we will do here. There is a simple way to focus on only the first enemy (Inferno) at the beginning. The second enemy (Stronghold) can be crippled in a blitz. Then, with superior economic and population, it is only a matter of time to take down the last and toughest (Necropolis) faction.
While the mission has a high level cap of 24, you will have plenty of huge battles to fight to reach the level cap long before the final boss battle. Also, as you are able to unlock more buildings and creatures, you will be short on cash to recruit all available units. So it is a good practice to cash every chest.
Necro Campaign Mission 3Level Cap: 24
Difficulty Index: 4/6
Last Updated: November 12, 2011
BASE
If you play on Hard Difficulty, for the starting bonus it is a good investment to get the 5 Wood + 5 Ore bonus, since you would start with none of them. You want to start building your primitive town right away.
The mission begins in the northeast corner at Town (A). Ana is given a puny army, which is much smaller than the neutral stacks nearby. However, by now your Ana build should have matured. Open every battle with Summon Earth Elemental right in front of the enemy line. With the enemies occupied with the summoned creatures, you can wear them down with Ana's direct attack.
Earth Elemental is the best among all the elementals for tanking purpose. Their special ability petrifies a stack for 2 turns, enabling you to concentrate on other enemies. They also carry a build-in Regenerate, which can be stacked with your Regenerate spell. Against living creatures, you can even slap a Life Drain on the Earth Elementals.
Whenever your mana drops to about 1/2 full, do a Meditation to refill it to the top. From now on, you will never run out of mana except for the toughest and longest boss fights (Meditation can be used only once per battle).
In your Town A, aim for the Archlich building and the Fate Weaver building (customize a market-friendly generic hero to regularly trade for gems) as soon as you can. The toughest battles of this mission and the next are almost exclusively castle assaults. Your success relies almost solely on the power of your ranged units. Great news: Life Drain also heals ranged units. The bigger your ranged stack, the more they damage, and the more they heal. The Fate Weaver (tier-7 upgraded creature) can transform into a very powerful ranged unit.
Make a round trip of your surrounding area, flag the Sawmill and Ore Pit, and head south to the neutral area to claim Fort (B). Clear everything with your Earth Elemental.
For the next step, you can either go southwest or southeast from here. If you go southwest and step in the friendly Necro territory of Town (G), you will trigger a conversation and suddenly have to face two additional enemies coming through the opened gate at (1). That's never a good idea while your army size is still miserable. Go southeast first and claim yet another neutral fort (C) and all its riches.
Now is a good time to hire a secondary hero to ship you the latest town productions to Ana. If you have reached the Bronze rank in your Dynasty, it is a good idea to pick up the "free first generic hero" trait as one of the starting bonuses in mission 3s and 4s. These generic heroes can cause a fortune at high levels.
Now your home base is secure and prospering. Let's deal with our first enemy - Inferno. Head down the stairs at (2).
INFERNO
The underworld is a very large area, with its only exit to the surface right where you are (2'). Ana will be down here for quite a few weeks, so better get used to shipping units from home. An Advanced Town Portal really helps. When you have some extra cash, hire the second secondary hero so you can ship the new units to Anna more efficiently.
Your objective down here is to defeat the Inferno faction (as a large and difficult side quest). The demons send a constant string of quite powerful army your way. You might have to face the first invading hero not far away from (2').
Follow the paved road down and clear a small area with a creature building at (3). Then go west to take down the Inferno Fort (D). Inferno heroes might try to reclaim Fort D, so stay close to sweep the nearby neutral stack first. In my game, I actually fought a rare defensive siege battle here.
After a while, the Inferno invasion will stop. In my game, I pushed back all the way to the final town of the Inferno faction, but only managed to defeat the smaller army camped outside the gate. Then I came back to take the second Inferno Fort (E) and clear the surrounding area. You might be able to save a few days to go after Fort (E) earlier.
There is a neutral area north of Town (D). Here is a side quest which gives you the Dynasty Weapon Staff of Sandro, located at (4), and the ability to hire the Tier-5 Necropolis creature. In my game, I postponed this side quest until after I defeated the Inferno faction. I also continued using the Soulreaver staff instead of switching to Sandro's since I really like the former's +5 initiative effect. The Staff of Sandro is an enemy army debuff weapon, which, if developed, could be quite handy in very large encounters.
With 1 town and 4 forts, you are now in a great position to take on Inferno's last stand, Town (F). There are various one-time or one-week combat bonus buildings to visit, though the AI frequently deploys one additional hero at the town's entrance to negate your advantage. On the bright side, killing them also makes the army inside the town a little smaller. You can also select "Retreat" (instead of Attack) before the second battle starts, so you can renew some nearby battle bonus.
Assaulting Town (F) is by no means an easy task. It has a unique structure that deals a lot of damage (300+) to your every stack at the beginning of every turn. (And this is the only occasion in the entire Necropolis campaign that you will see it.) A lot of players reported trouble of this battle in particular. You are most likely killed faster than you can heal. If you find it too difficult, take more time to gather a larger army, since you can outproduce the Inferno faction now. Eventually, you will be able to overpower it. You can use the idle time to solve the Staff of Sandro side quest.
I tried this battle as early as I could win, and ended up losing the majority of my army, coming out with only 90% of the Ghoul stack and 12 Archliches. But here is the beauty of Necropolis - I simply go broke at Town A to raise most of the fallen units (requires the Alter of Eternal Servitude unique building)!
STRONGHOLD
Finally, you can walk Ana all the way back to the surface. When she almost reaches the exit (2'), send a secondary hero to the friendly Necro territory of Town (G) to trigger the gate at (1) to open. You are now only steps away to face the boss of the Stronghold faction.
While you might see minor Orc heroes roaming around, your primary objective is to defeat a stationary Orc hero in front of Town (H). This is not really a difficult fight compared to Town (F). It is not even a siege battle. After winning this battle, you automatically take possession of Town (H). It will be a very underdeveloped town, though.
Two down, one to go. You should receive a message to meet with Ludmilla at Town (G). Do it as soon as possible, since that will give you another free town. On your way to Town (G), get a free look of several islands and their goodies at (5).
After completing Ludmilla's quest, you should be able to grab everything that formally belongs to her, whom personally joins your roster (don't forget to assign all of her abilities points). In my game, I could attack Town (G) but only after I loaded a save for an unrelated purpose. That gives me a fully developed free necro town. As for town development, put a priority on ranged units. All your remaining tough fights are castle sieges.
By the way, at this time you should have reached level 20, which enables you to "respecialize" all of Ana's spent ability points (one-time only). If you have wasted points into spells that you never used, this is the time to redistribute them to something else. There won't be any more "respecialize" opportunity after this.
Around this time you should start seeing oversea invasions from the hostile Necropolis faction. They like to land close to (6) and try to steal Town (H). Pretty much like the Inferno faction, they will keep coming until you make an effective counter-invasion. But let's finish local business first.
When you are done with clearing the surroundings of Ludmilla's Town (G), go southwest to claim Fort (I). It might be still under the Orc's control, or the Necro faction has stolen it from them. After finishing local businesses, load up Ana with a gigantic army and set sail! There are two shipyards (SY) you can use. Or you may actually pick up a few abandoned ships from the invading Necropolis army.
THE STRAIT OF JADE
Before launching the final invasion on Miranda's Necropolis faction on the other end of the strait, there are quite a few things you can do on the islands - two Shrine of Seven Dragons (SD) and more stat boosts. I recommend not using the shrines at all, since you need the Blood Crystals for units, and you will have enough EXP to reach the battle cap anyway.
On the central island you will come across the strangely colored Heroes6 Phoenix (higher flame temperature, maybe?). While they seem to forget about their rebirth ability, try to avoid any melee attack on them. Each physical contact gives you a fixed amount of irreversible damage - these units are gone for good for the battle (you can still buy them back at home). Since your Ana is away from home, you don't want her to lose a sizable army on an optional neutral creature encounter. Powerful ranged stacks, combined with Time Stasis, Earth Elemental's Petrify ability should bring you perfect victories here.
Once you are done with the islands, go south to land on the other side of the Strait. There are actually two landing beaches. The southern beach leads to you to Town (J) which is probably still under the Orc's control. The northern beach leads you to a Necropolis Fort (K).
While Ana is away, the Necropolis faction might launch more attack from the sea. It is a good idea to let a hero carry the newly recruited units for defense just in case. Ludmilla is ideal for this task. After the invasion stops, she can ship her army to Ana for the boss battle.
MIRANDA
Your first goal is to take Fort (L), followed by Town (M), which should be defended by a quite powerful Necro hero. While you want to minimize losses, you can immediately buy back the fallen units at Town (L).
You are just two steps from victory! On your way north lies Fort (N). The final fight takes place at Town (O), guarded by a very powerful Miranda. In my game she carries 110+ Fate Weavers and hundreds of other creatures. While even quick-combat assigned me the victory, when I fought this battle manually, I ended up walking out with just 20% of my army.
If you find Miranda too powerful, there are various combat bonus buildings to visit. By now your unit production should totally overwhelm Miranda's. You can pass the time by fighting some more neutral stacks to accumulate more Dynasty Weapon and your account's EXP. Eventually you will overpower the boss.