Map 3 - The Defense
Size - Very Big
Carry Over - Findan, Talanar and Dirael
Level Cap - 24
Although the map size says "very big", this map is rather simple. When I say simple, I mean the landscape is not complicated; I don't mean the mission is easy. It is far from easy on heroic, especially after patch 1.2. You start the mission with a mandatory siege battle, defending the Sylvan capital. This is the only battle in the entire campaign story that you are supposed to lose.
However, before your troops die, you can make good use of them. Concentrate your attack on the skeleton archers, and you should be able to wipe this stack out. Your castle moat might also do you a favor by killing one or two high level creatures.
After this, it is Findan's turn to assault the castle. They AI's will concentrate their fire on your sprites, and then the dancers, so keep them defending all the time to delay your hunters from being the next victim.
If the enemies stay inside the castle wall, you will have a very difficult time especially after patch 1.3 toned down the ranged damage from outside the wall. Fortunately, the AIs are scripted that when it loses its ranged force, its melee units start to rush out (and get ganged up by yours). The key is DO NOT rush any unit in before that happens, or they will never come out. You know they are coming out when their melee units start to move. This may happen only after the AI loses a fraction of their ranged power.
It helped me a lot to march my treant forward, blocking the castle gate to take the heat. The AI units will come out to attack the treants from multiple directions. Then, our other units can now mop up to get rid off them. Try to conserve your emerald dragons as much as you can (don't fly them in!), because you won't be able to replenish them for a while, and they are very useful elsewhere.
This castle assault is very important for the entire mission. If you fight it well, the subsequent battles will become much easier. If you learned Resurrection back in mission one, resurrect your sprites back before the end, as they will save your most-valuable-hunters in the coming battles.
Now you have the capital back, which is good. Let me explain a little what lies ahead. You are up against the teal player, who owns two towns, one Sylvan and one Necro. The Sylvan town on your SW is relatively close to your Sylvan capital, so it is a good idea to rush it with Findan. This is particularly important on heroic.
The bad news is purple heroes are coming to attack your capital constantly (similar to mission 5 of the Haven campaign). In fact, the next purple hero has already spawned while you are celebrating the liberation of your Sylvan capital! It only takes two days for them to start the siege. You get no more chance to retake the capital. You lose this mission as soon as you lose the capital the next time. In patch 1.3 you will see 3 more purple heroes in the first week, so it is possible that your low-level hero cannot survive, and you will have to keep Findan home to defend for the first week.
After the first week, you can expect one purple hero every one or two weeks. The strength of the attacking armies grows slowly, too. If you are playing at a high difficulty, you really don't want to keep Findan in the capital, because the purple heroes never stop coming, while the teal AIs never stop building until you force them to. ;) Here is what I recommend:
On Day 1, hire a new hero, swap his army with Findan's, and send Findan on the boat with the new hero's little army. You will use this new hero and 100% of Findan's leftover army to defend the first few purple heroes. The key here is to leave ALL your shooters (hunters and druids) with the new hero or you will lose simply too many melee units from their liches. Findan does not need the hunters to take towns, but you need them to defend towns.
You might also want to hire yet another hero to sail out to collect debris and chests. There is a bunch on your east, and after passing the whirlpool there are two more piles nearby. You can collect a couple dozens of logs from the initial investment of 10.
When the first purple hero comes, try to kill them off as soon as you can, even if it means losing a dragon. Ancient treants are excellent at blocking a breached wall, while the unicorn takes care of any enemy unit trying to get inside. Sprites and war dancers will become your damage sponge. Without them the enemy will target your hunters, so don't feel bad about their loss. After patch 1.2 the AI hero might drop some mighty spells (such as chain lightning) on your hunters. Too bad - there is no way to avoid it. On 1.3, though, the AIs seem to lost the ability to cast these spells, possibly due to the 200% mana cost.
After the first defensive battle, you can set the favorite enemy for your defending new hero. You can "update" your favorite enemy list whenever a new purple hero spawns (right click on it to check what it carries). I would highly recommend liches, and possibly vampires. They are very hard to kill.
The initial waves of assaults are the most difficult. If you have lost almost all of your hunters and druids (which happened to me every week after patch 1.2, but not 1.3), you might need to use Quick Combat at some point to save an otherwise impossible battle. Just to stay alive - your pain will be over soon.
Meanwhile, quickly sail Findan to the west and then south after you see the lighthouse. Your goal is to land at the shipyard at (1). Then, the Sylvan town is only two day's travel to the west. Now it is the time for Findan to summon all emerald dragons. These flying units are excellent for a quick siege battle. You should be able to take the Sylvan town with minimal loss before the first week even ends. Also, you will see an undead teal hero hanging around. Your emerald dragons will make sure they stay dead this time. If you don't see this hero around, be careful that he will try to make a run at your new town. Hunt him down as soon as possible.
Now you have two towns, and the teal player only has one. You can finally flag mines, so your victory is coming slowly! Your next goal is to get a lv 5 mage guild in one of your towns (better at the new Sylvan town, because Findan is nearby). Since patch 1.2, heroic, you have few starting resources and you don't really want to waste any of them on the buildings. Patch 1.3 made some adjustment to the resource requirement, but you are still very short on the rare-material side. If you haven't got it already -- you are shooting for the Resurrection spell. If you get Word of Light, which is almost useless, then try the other town. If you don't get it in either town, too bad. (I would restart the mission right here, but you can certainly press on and see what you can make out of it. You get 2 more chances to learn it in mission 5, but you can't get it early.)
On higher difficulty your capital is probably falling apart, so you may want to start rush Findan back to accumulate some army. It would be a really good idea to ship the new Sylvan town's growth back to the capital. In addition, there is a landing dock at (2), and a hunter's cabin nearby. If you are patient and would like to have 7 more hunters per week to defend the city, you can hire another hero to ship hunters to your Sylvan capital weekly. The teal heroes might be chasing after your low level heroes, and they will try to summon a ship if you leave one hanging. Better be careful than sorry.
Once you have Resurrection, you have successfully turned the tide of the entire campaign. Your emerald dragons, or everything Findan carries rarely dies from now on. Now Findan can break through the two garrisons (3 and 4) with a dragon-only army and laugh at the defending stacks.
After passing both garrisons, you have a choice of taking the remaining teal town or rescuing one of the two Sylvan prisoners in the jail at (5).
Note: One obvious change of patch 1.3 is that the two heroes you are about to rescue will have a pre-set level of 28, and 5 skills paths pre-developed (see the attached pictures). This means that you no longer have the freedom to develop their 6th skill, unless you happen to grab something useful from the Witch Hut underground in this mission. The two heroes also have very miserable stat point distribution -- highest spell power for a hero who knows little magic, and lowest spell power and knowledge point for a hero who use exclusively magic. Good job, Nival. Or maybe that's why they are incompetent and ended up in prisons.
The jailed hero at (5) is Talanar. He is a typical might hero, with no magic ability at all. He suffers from some low ATK and DEF stats, but he is still an awesome hero due to his Nature's Luck ultimate ability, which makes all physical attacks lucky (rainbow).
If you choose to rescue Talanar first, you can send him directly back to the capital to defend, and watch rainbows fly to the moon. If you are playing at a lower difficulty, or you have seriously messed up Findan's build, it would be nice to give Talanar Enlightenment or Light Magic to fix his weakness. Otherwise it doesn't matter -- you won't bother giving Talanar any army in the last mission because Findan is simply a better army leader. Make sure that Talanar learns town portal and summon creatures in this mission, though. (requires lv20 hero & lv5 mage guild)
The teal town is manned by a moderately powerful Necro hero. If you are fast enough, you might have scared him back to his castle by now. If you are slow, then he might have attacked you already. At this point you are definitely more than capable of disposing him without losing any dragons.
After wiping out the teal player, you need to rescue another hero, Dirael, a summoning specialist. She is held in an underground prison (6). The stairway leading to it is SW to the Necro town. Prior to patch 1.3, Dirael also starts with Nature's luck and does not give up a precious skill slot for the now-redundant Luck skill. For the 2 skills you can customize for her, I would highly recommend Light and Enlightenment, which boost her mana (Intelligence) and spell power (many more fire elementals), as well as giving her the precious Resurrection spell. She will become very useful in the last mission. Dirael is an army by herself!
Note: Patch 1.2 and 1.3 seriously toned down Dirael. Her Nature's Luck special ability is removed since 1.2, and in 1.3 she does NOT receive any extra stat point from her preset Expert Enlightenment skill. Combined with the removal of stacking elementals, she is now much less useful in mission 5.
Once you rescue Dirael, take your time to level the two heroes up (not necessary for patch 1.3) and explore the map. Your only remaining objective is to stock up enough troops in the garrison. (See the in-game mission objective to reveal the exact numbers you need.) If you have been buying units there, then you might have already fulfilled this objective unwillingly. To avoid the frustration of not being able to level up everybody to the cap before the map finishes, do not stock emerald dragons in your capital (you only need shooters for the defense, anyway).
When you are done exploring and levelling, take both heroes back to the Sylvan capital, swap them in and out the town, and the mission should be completed.
Note: Some people have reported bugs that the mission cannot finish, even if they have done everything required. If this happens to you, try this: Move Findan inside your capital, and the other two outside. Then purchase a new hero from the tavern. Also, you might need the latest patch (1.3 when this article last updated).