Warcraft III: The Frozen Throne Walkthrough & Game Guide

Mission 4: The Return to Northrend
Three weeks later, King Arthas' Ragged Fleet drops anchor off the icy southern
coasts of northrend.
Arthas starts off this mission at level 7.  Start off the mission by moving all of
your forces into transports and then moving them to the north, destroying the
human ship, dropping your forces off and destroying the human encampment here.
Use meat wagons on the towers and raise dead if you need to.  Make sure you kill
all of the buildings. After a cut scene you'll get a new main quest, and an
optional one

Start off by building a crypt (at least one), a graveyard, and an altar.   Along
with a few more ziggurats.  You can tech to the halls of the dead now if you wish.
While you are waiting for things to build, you can go around and break the barrels
to get more gold and lumber.
When your crypt finishes build some ghouls and put them on wood.  When you are set
with ghouls, start building fiends.  I suggest going fiends and banshees or
necromancers  or possibly some obsidian in this mission.
When your halls of the dead finishes build a temple of the damned for casters and
a slaughterhouse if you are getting obsidian statues (don't forget to build a tomb
of relics).

When you have around 60 food worth of units I would do the optional quest.
Optional Quest: Dragon Hoard
-Slay the dragon Sapphiron
Head north with your fiends (you should have a lot of them).    You'll know you're
going in the right direction if some drakes and whelps attack you.  Kill the first
group and then head north, for another group (it's more powerful, but it doesn't
really matter as fiends will own them).  Head southwest along the path and fight
some more blue drakes and a blue dragon.  Head north from here and fight
sapphiron.  Not only is he difficult two blue dragons guard him as well.  It will
be very difficult but use animate dead you should be fine.   When he dies you'll
get a GIANT frost wyrm (that does piercing as opposed to magic), with frost nova.
Take the horn of the clouds it is very useful.  Head to the west and take all of
the items.
IF you have sapphiron you should be fine, but build up your forces some more and
go to the shipyard to the north.  The invulnerable ice bridge will shatter.  Bring
up your forces and take out the  ships to the west with sapphiron or battleships.
Then head north and drop of your forces at the naga base.   The base should fall
very fast with your units (especially if u have sapphiron).  When the base is
sacked start heading to the west .   Kill the shorecrawlers. Then kill the kin g
arcachnadtid.  Then kill the nerubians to the north, then go through the multiple
nerubian bases and then kill the guardians next to the green circle.  With
sapphiron this should be very easy, but if you've been upgrading your crypt fiends
and necromancers it should be even easier.  Using animate dead at the  When they
are dead the mission is complete.