Banshees were once beautiful female Night Elves who were brutally murdered by demons during the fall of Kalimdor. Their restless spirits were left to wander the world for many ages in silent, tortured lamentation. Over the years they became jealous of the living and seeded a deep hatred for all life. Yet when the Lich King, Ner'zhul, became aware of them, he gathered them together and promised them vengeance upon the living. Ner'zhul gave them terrible voices so that the living would finally hear their timeless anguish. Thus, the Banshees have pledged themselves to the Undead cause and serve as valuable warriors in the Scourge. The spectral Banshees can fly and are fond of hammering their enemies with tortured blasts of sonic force. Their unnerving, unholy screams can be heard from miles away.
Banshees are very good at supporting units, coming with their initial spell of Curse and can later learn Anti-Magic Shell and Possession. They're still fairly weak like Necromancers and need protection. Banshees are the bane of any army that is heavily invested into ground units, as they can steal them and turn them against their owner if given the chance.
Spells and abilities
Curse (Autocast)
Curses a target enemy unit, causing it to have a 33% chance to miss on an attack.
Duration
Cooldown
Mana Cost
Range
Area of Effect
Allowed Targets
Effect
120 (60) sec.
1 sec.
40
70
N/A
Air, Ground, Organic
33% chance to miss
This is a very useful spell in intense battles as this makes units more likely to miss, which stacks up when their attack speed is boosted. Curse is automatically set to cast on enemies, but disable it so she does not waste mana on insignificant skirmishes.
Counters
Dispel, or use Spell Breakers to remove the curse and transfer it to an enemy unit.
Anti-magic Shell
Creates a barrier that stops 300 points of spell damage from affecting a target unit.
Duration
Mana Cost
Range
Allowed Targets
Effect
Requirements
90 sec.
75
50
Air, Ground
Absorbs 300 points of spell damage
Banshee Adept Training
This protects a unit from spell damage that could otherwise kill them, such as the Mountain King's Storm Bolt or Warden's Shadow Strike.
Counters
Dispel the anti-magic shell.
Possession
Stuns a target unit and the Banshee for 4.5 seconds, during which the Banshee takes extra damage from attacks. She then displaces the soul of the enemy, giving you permanent control of it, but destroying the caster's body. Possession cannot be used on flying units, Heroes, or creeps above level 5.
Mana Cost
Range
Allowed Targets
Effect
Requirements
250
35
Ground, Non Hero, Enemy, Organic, Neutral
Converts unit to your side
Banshee Master Training
This spell is highly effective in taking over enemy ground armies by robbing them of their own units. When a Banshee possesses a unit, your food value can change. A Banshee costs 2 food; if she possesses a Tauren, then the player's food would rise 3 slots because a Tauren costs 5 food. Note that this can cause you to rise to Low or High Upkeep and may also prevent training further units or reviving a slain Hero if it goes over your food cap.
They can be used as an alternative to a Dark Ranger if a player wishes to access the tech trees of other races, but the only disadvantage they have over her is that a Banshee cannot be used to possess an aerial unit.
While attempting to possess a unit, both the Banshee and the targeted unit will be frozen in place. A white orb will also appear over the Banshee indicating a possession attempt.
Counters
Possession is channeled spell, and thus can be interrupted as with any other channeled spell. The Banshee is not invulnerable when she attempts to case Possession, so killing her before she possesses her target will also work. Aerial units or units possessing spell resistance/immunity can also work.
Upgrades
Banshee Adept Training
Increases mana capacity by 100, mana regeneration rate by 30%, hit points by 40, and gives them the ability to cast Anti-magic Shell.
Research Cost
Researched At
Upgrade Time
100 50
Temple of the Damned
60 sec.
Banshee Master Training
Further increases mana capacity by 100, mana regeneration rate by 30%, hit points by 40, and gives them the ability to cast Possession.
Research Cost
Researched At
Requirements
Upgrade Time
100 150
Temple of the Damned
Banshee Adept Training, Black Citadel
75 sec.
Backpack
Gives the ability to carry up to two items. Items carried by the unit will be dropped upon death.
Units can not use or gain benefits of items that they carry.
Research Cost
Researched At
Requires
Upgrade Time
50 25
Townhall-type Structure
Player-built Shop
20 sec.
Any items in the inventory will be dropped upon successful Possession.
Possession has been reworked. It is now a channelled spell with a 4 1/2 second casting duration. During this time, the target is disabled and frozen into place, but is also invulnerable; and the Banshee takes triple damage from all attacks. Stunning or killing the Banshee that is casting Possession will cause the spell to abort. Additionally, the range of Possession has been increased to 350 from 200.
Anti-magic Shell has been redesigned. The spell now absorbs the first 350 points of spell or magic damage dealt to the target, but does not grant magic immunity. Note that spells absorbed by AMS can still deal secondary effects, such as stun, paralysis, or mana drain. Also the mana cost of AMS has been re-balanced to 150.
Most spellcasters (Sorceress, Priest, Shaman, Witch Doctor, Necromancer, Banshee, Druid of the Talon) have been re-balanced. In general, units with piercing damage rip up spellcasters, while basic melee units, such as Ghouls or Footmen, are weak against spellcasters. The specific changes to the units in question are:
They have a new armor type, unarmored, which takes bonus damage from siege and piercing attacks.
They also have a new damage type, magic, which does reduced damage to fortified and hero armor, but does bonus damage against medium armor.
They had their damage adjusted, typically downwards.
They no longer gain damage as they go up in level, and gain less hitpoints as they go up in level (but start with more hitpoints when initially built)
Many autocast buffs and debuff costs reduced.
Casters, including Dryads, have had their mana regeneration rates boosted by 30%.
Curse now causes a 33% chance to miss, up from 25%.
150 
Patch 1.14 (2004-01-07): Anti-magic Shell cost reduced to 100 from 150, and hit points absorbed reduced to 300 from 350. 
Patch 1.06 (2003-06-03):
Battle.net Warcraft III - Undead -> Units -> Banshee
