Warcraft III: Reign of Chaos/Undead strategies

Tactics
The Undead are a very involved and interesting sect to play as. Their control over the undead creates for a great many opportunities to mess around with and create hordes of new troops. One idea, courtesy of Meta Physical, relates to creating the "Main" fighting army of the following units:

1 Death Knight (Preferrably level 6 or above, with "Animate Dead") 3 Necromancers 3 Meat Wagons

It goes without saying that these troops work better with upgrades, especially the Necromancers.

Fill the rest of the ranks with preferably ranged troops, as not to get the area damage that the Meat Wagons dish out with each corpse launched. Recommended are Crypt Fiends, for their "Web" ability and cheapness/effectiveness, and Frost Wyrms, for their excellent damage, flying ability, and "Building Stall" Freezing Breath upgrade.

The Meat Wagons should load up as many corpses from local brawls or Crypts as possible, before the "fun" begins. The Necromancers should have at least half of their mana bar filled, also.

With the dozen units finished, you may now go and explore the map. A scroll of Protection is recommended, also, as to protect your Meat Wagons from soaking up too much damage, as they cannot be healed with Death Coil.

When encountering a large army, or an enemy fortification, the following actions should be taken, in order.

1. Attack with all troops. 2. Upon reaching the fray, have the necromancers turn on "Auto-Animate" by right-  clicking "Animate." The Meat Wagons should drop corpses, accordingly to the needs of the Necromancers. With 3 Necromancers, it should take only seconds to create a large melee force, while your ranged units attack from a distance. 3. In a particularly trying fight, it is very recommended that "Animate Dead" is  cast by the Death Knight. This will raise any dead troops, friend or foe, keep in mind. Any animated troops should independently begin to fight, if in a base or a battle. 4. The animated undead will spread randomly, attacking the closest enemy target. To control them better, double click one of the troops (works well with skeletons, but not with "Animated" corpses) and orders may be very easily given out, then.

This mix of ranged combat, with an on-the-spot "deployable army" is a very easily used tactic, and is perfect for beginners and experts alike. It has been tested on Hard difficulty, in the Undead single-player missions, and online, and has come out successful in the hands of most players.

The counter: Simple, Dispel them with your Spellcasters. The skeletons can't take a hit and the Animated dead deals itsy bitsy damage.

Alternate tactics
Start by building an Altar of Darkness and Crypt to produce a Death Knight and 3-5 Ghouls. Upgrade your ziggurats to spirit towers as quickly as possible. Maintain defensive position until you unlock sacrificial pits. Then plant shades around the map, and wing it.

Playing Tricky
One tactic, submitted anonymously, requires the use of the invisible scouts of the undead: The Shades. The strategy works only with opponents who do not equate in invisible troops in their plan of attack, and therefore proves quite effective against most crowds.

Create 6-8 Shades from idle workers. Scour the map in search of the enemy hero, preferably in the "wilds," as opposed to a base. Order the shades to "Follow" the Hero by right clicking him, as if to attack. The Shades will crowd around the Hero, and render him "stuck."

This body-block trick is bound to drive many crazy, as can perhaps be seen as a bug by all by the most brazen player, when used against them. The Hero may then be left "to rot" (assuming the opponent doesn't have him killed and resurrected, first) or killed for experience or spite.