To win, you must have a total of 2500 Skeletons in all your armies within 3 months. Some Border Guards can only be passed if a Hero carries a Quest Artifact from a previous scenario, but the artifact beyond the Border Guard will travel with you to the next scenario. Starting Bonus: Vampire's Cowl or Necromancy Amplifier or Unearthed Graves.
Click on a map to see a larger version.
Green - Friendly Town
Red - Enemy Town
Grey - Neutral Town
Yellow - Underground Passage
A# - Allied Towns
O# - Opponent Towns (a,b,c,d,e,f,g indicates which enemy)
N# - Neutral Towns
M# - Mirror Entrances (a) and exits (b). two-way unless stated
E# - Exit (a) entrance and (b) exit
S# - Seer (a) and the location of the item (b)
G# - Guard Tents (a) and the location of the Guard Tower (b)
J - Jail
X - Ambush
Take the Vampire's Cowl as your starting bonus as you will easily be able to build the other two buildings. The Vampire's Cowl will provide a long-lasting benefit to Vidomina who has the Necromancy specialty and she should be your main hero because of this. There are no enemy heroes on this map so you don't have to worry about anything except getting as many Skeletons as possible.
Have Vidomina get all of the troops from your town and head south on the pink path to meet with Vokiel to get the Vampire's Cowl from him as well as his troops. There is a boat to the west of Vokial that you should get on so you can take over O2a. You don't need to do this but you can transform the creatures produced in the towns to skeletons which will really help with your goal. It will also help with transporting all of the troops to your town to convert to Skeletons once you get the Town Portal spell.
After defeating O2a, head on the teal path to take over O1a which shouldn't be very difficult at all. Once finished, head back south to free Sandro from the jail and to get the stacks surrounding it since they will all join you. Just be sure you can accept the new creatures into your army so consolidating troops with Sandro will work out well. You do need the Spirit of Oppression to get past the Quest Tower but the artifact will carry over from the first map. Now continue south on the orange path and take over O1b which will result in the defeat of all of the enemies.
There are a few ways to get very many Skeletons. You should attack all of the wandering stacks, not let any of them run away, and to let them join if they want to. You can always put the joined stacks in captured towns to transform into Skeletons later. Always be sure to protect your Skeletons in battle and only use them to attack when there is no chance of retaliation. Town Portal is a helpful skill because it will let you visit all three captured towns, hire the low-level troops, and transform them into Skeletons. When you have 2500 Skeletons, put them on a hero and leave the town since the Skeletons who are in garrisons don't count towards the goal.