Warcraft III: The Frozen Throne Walkthrough & Game Guide

Mission 3: The Dark Lady
Two Days later, at her base camp in the newly formed Plaguelands, Sylvanas ponders
her newfound freedom and her future as one of the cursed undead.

You can't build much in this mission, just banshees, obsidian statues, meat
wagons,  and ghouls.  Build banshees, banshees and more banshees.  A few obsidian
statues will do you well.  Some abominations will come and attack your base.
Possess them.  This is how this mission goes.   Deactivate curse, and have your
obsidian statue build up mana for your banshees.   If you don't do any optional
quests for this mission all you'll have is undead units,.   Head to the north
across the bridge.

You'll fight some ogres, possess them if you want., and you'll get the first
optional quest (well I do it first, even though it is the second)

Optional Quest: Ogre warlord
-posses the warlord ogre Mug'thol
The trick to getting a ton  and I mean a ton of units is to ignore everyone but
the ogre warlord.  Just let yourself get attacked and have your banshees possess
the ogre warlord.  They show you where he is on the minimap so just  make your way
through the ogres, do not kill them, break the rock chunks and then  O+click on
him with your group of banshees if all goes well you should have a TON of ogres at
your disposable.  Oh and to make it EVEN BETTER, they don't count  for the food
You get
5 ogre magi
4 ogre brutes
4 ogre wound masters
and Mugthol (he does a ton of chaos damage and has a ton of health)

You can do the same win the second optional quest.

Head across the bridge towards the middle of the map.    Kill the red undead
forces or possess them.
Optional Quest: Bandit lord
-possess blackthorn the bandit Lord
Break open the gate to the north and then do the mad rush to blackthorn like you
did with the ogre warlord.  Possess blackthorn.  You will get
3 renegade wizard
4 brigands
8 enforcers
8 assassins
and Blackthorn.
When you are ready (which you  should be because you have so many units All you
have to do is head into the red undead base.  With almost no micromanagement you
will run straight through them.  If you didn't do the optional quests than you
will just have to possess the abominations and make your way through.  When the
base is destroyed your mission will be complete.