Warcraft III: Reign of Chaos/Frostmourne

Chapter Introduction
The next day, at Arthas' base camp...

Mission Objectives
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 * Main Quest - Frostmourne
 * Locate Frostmourne
 * Arthas must survive
 * Muradin must survive

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 * Main Quest - Mal'Ganis
 * Destroy Mal'Ganis' base

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Strategy
From the beginning, your forces are divided, and you can't move your forces from one group to another. In order to succeed, the player needs to take care of both groups simultaneously. This guide recommends shifting your attention frequently between the groups, keeping both moving at the same time. While this may be difficult to do effectively, defense is significantly easier once your forces are no longer split.

Arthas and Muradin
While only Arthas and Muradin must be kept alive, do try to keep the rest of your group alive as well. You don't get to keep them after reaching Frostmourne, but the sooner that point is reached, the better. The path generally goes to the north, making it feasible to order the group to Attack-Move north of their current position. This give you time to shift your attention away from this group for a while, without making them wait.

First they will encounter two Giant Frost Wolves and a Dire Frost Wolf. The Dire Frost Wolf drops a Ring of Protection +3. Next a Frost Wolf will briefly attack your group before running away. The Wolf leads you to an ambush consisting of two Frost Wolves, two Giant Frost Wolves, three on hard, and a Dire Frost Wolf. This Dire Frost Wolf has a Periapt of Vitality. Immediately beyond these Wolves, there's a Fountain of Mana. While it can be useful to increase the mana of Arthas and Muradin, this guide doesn't recommend that you dally. Next attack is on a clearing with two Frost Wolves, three on hard, a Wendigo and a Wendigo Shaman, also an Elder Wendigo on easy and normal difficulties, and an Ancient Wendigo on hard difficulty. The Shaman drops both a Potion of Greater Mana and a Tome of Agility. Soon your forces will reach a cemetery with four Skeleton Archers, two Skeletal Marksmen, a Ghost and a Wraith. It's clearly recommended to bring only Arthas and Muradin to the start of this fight, as the Ghost and the Wraith are capable of Possession. This ability destroys the caster, but permanently turns the target into part of the caster's faction. Arthas and Muradin are immune, and it's a big setback to have to kill one or two of your own Knights or Riflemen.

Lastly, there are two Skeletal Marksmen, two Frost Revenants and The Guardian. You can't attack any of them until The Guardian has said his piece. Feel free to take care of your other group while he's talking. Once you can attack him, focus your attacks on The Guardian, since the other enemies stop fighting once he's dead. After an ominous death speech, Arthas obtains Frostmourne in a cutscene.

The Captain
While the Captain has been entrusted with running the base, it isn't necessary to keep him alive. It's, however, useful, since the Captain is a powerful unit that doesn't count towards your food limit. You start the chapter in low upkeep, and this guide recommends keeping your upkeep low. To begin with, recruit five more Peasants, two more mining gold and three cutting lumber. Unless some units have died, more can't be recruited without entering high upkeep, so use resources on researching upgrades.

The first attack on your base will happen at both the north and northeast entrance. It's therefore useful to move the units stationed at the east entrance to one of the other entrances. All later attacks happen at one entrance at a time; see the table for details. Typically, the Green Undead forces attack from the north or northeast, while the Purple Undead forces attack from the east or northeast. For an early warning system consider stationing the Gyrocopter where it can see both approaches, but not be reached by ground troops. Note that Purple doesn't have any Necromancers, Gargoyles or Frost Wyrms; only Green attacks with these units.

While it's completely possibly to be industrious and attack before Arthas returns, it's harder to do without the aid of Arthas' abilities, and difficult to coordinate while keeping Arthas' group moving. This guide recommends leaving your units on defense and researching upgrades. Shift your attention over to Arthas' group when upgrades are being researched and the base is not currently under attack.

Mal'Ganis
Once Arthas has obtained Frostmourne, he'll reemerge entirely alone from the Way Gate, to be greeted by the Captain. Have them join your other forces. This doesn't go unnoticed by the Undead, which change their attack pattern in response; see the table for details. Notably, Mal'Ganis now also joins the attack waves. He's Level 9 on easy and normal difficulties, Level 10 on hard. He casts Level 2 Carrion Swarm, Level 3 on hard, and Level 3 Sleep. Since the Knights and Riflemen from Arthas' group no longer count towards your food limit, additional recruits can help defending against the coming attack waves. Muradin's inventory can be found back at the base.

When not under attack, take the time to explore. Exit by the north entrance to find a tiny Undead base. They don't have the capacity to launch attacks, but they control a Gold Mine that can be useful. Exit by the northeast entrance and take a left to find three Spiderlings, a Nerubian Webspinner, a Nerubian Seer and a Nerubian Spider Lord. The reward for killing them is a Potion of Mana, a three-pack of Healing Wards and access to their Gold Mine. Go down the ramp and cross the frozen lake to two Ice Trolls, an Ice Troll Priest and an Ice Troll Berserker. Killing them yields a Potion of Greater Healing. Exit by the northeast entrance and take a right to find this chapter's Mercenary Camp. It hires out Nerubian Warriors, Ice Troll Berserkers and Frost Revenants. Since they can't be hired by anyone but Arthas, they're not all that useful by the time they're available. Continue circling the frozen lake counterclockwise to a Goblin Merchant. Exit by the east entrance to find the Purple Undead base. Destroying this base isn't a requirement for victory, but it's easier to destroy the Green Undead base if the Purple Undead aren't attacking your base simultaneously.

At some point, there aren't any more useful upgrades, so recruit a full army. Just as an attack wave from The Green Undead has been defeated, launch an attack on the Purple Undead base. Send Arthas and the Captain along with Priests, Sorceresses, Steam Tanks, Knights and Gryphon Riders and attack the Purple base. The units defending the Purple base are largely the units intended for the next attack wave. Have Steam Tanks in front, so they can demolish buildings quickly. Once all Purple units are dead and all Purple unit-producing buildings destroyed, retreat all your units except the Steam Tanks. The next wave by Green might be imminent, and the Steam Tanks can mop up any remaining buildings alone. For the sake of completion, an Ice Troll Priest, two Ice Troll Berserkers, an Ice Troll High Priest and an Ice Troll Warlord are located north of the Purple base. Killing them yields a Health Stone.

Replace any units killed during the attack on the Purple base, and attack the final Green base in the northeast corner of the map. The units defending the base are mostly the units due to be included in the next attack wave, but there's also a single Shade, an invisible Undead scout, in the base. Once the entire base is leveled, both the chapter and the campaign is won.

Treasures

 * The first Dire Frost Wolf drops a Ring of Protection +3.
 * The second Dire Frost Wolf has a Periapt of Vitality.
 * The Wendigo Shaman drops both a Potion of Greater Mana and a Tome of Agility.
 * A three-pack of Healing Wards can be found on the Nerubian Spider Lord.
 * A Potion of Mana can be found on the Nerubian Seer.
 * An Ice Troll Berserker drops a Potion of Greater Healing.
 * Killing the Ice Troll Warlord is required to obtain a Health Stone.
 * The Goblin Merchant sells Potions of Healing, Potions of Mana, Scrolls of Healing, Scrolls of Protection, Wands of Negation, Gems of True Seeing and Scrolls of Town Portal.

Points of Interest

 * Any Scrolls of Town Portal and Amulets of Recall in possession of Arthas or Muradin are removed once the chapter starts. They reappear in your base once Frostmourne has been obtained.
 * The effects on Arthas of the Tome of Strength, the Tome of Strength +2, the Manual of Health and the Tome of Agility found in this campaign are preserved upon the completion of a chapter, and the advance into the next chapter, but aren't preserved when Frostmourne is obtained.
 * If you manage to kill Mal'Ganis before obtaining Frostmourne, he will revive by Ankh of Reincarnation. Each time you kill him, 3 or 4 Ankhs of Reincarnation spawn around the effecting Ankh. Internally he is given an Ankh of Reincarnation by the game every 1.5 seconds when alive, then you have to kill him 6 times in a row in less than 1.5 seconds to deplete all Ankhs before he eventually dies. After his death, Ankhs of Reincarnation keep spawning around his death spot. However, the mission will not be completed until Frostmourne is obtained.