Blackguard

Blackguard is one of the four class kits for a Paladin. While all paladins and the other class kits are only for lawful good aligned characters, this class kit is more like an anti-paladin kit, as they can only be picked by evil aligned characters and their abilities are adjusted to this.

Instead of Lay on Hands, they have the ability Absorb Health, which deals 2 points of damage per level to an enemy and heals the Blackguard the same number of hitpoints. While paladins and the other class kits can become fallen, blackguards are not affected by Reputation or the evil acts they perform. They can't use the spell Detect Evil and Protection from Evil as an innate abiliy.

They have an extra special ability, Poison Weapon ability. Gains one use at level 1, one use at level 5, and an additional use every 5 levels thereafter. Each successful hit within the next round injects poison into the target, dealing an extra 2 points of extra damage per second with no Saving Throw (for a total of 12 points of damage). Moreover, if the target fails a Saving Throw versus Poison, he will suffer 1 additional point of damage per round for 4 rounds.

Turn undead
Priest and Paladins have the ability turn undead creatures. When this mode is activated and the undead creatures are in range of the character, there is a possibility the undead will stop attacking their targets and run away from the character until the effect is worn off. At higher levels, this mode may destroy undead.

Protection from evil
This ability is like the spell Protection from Evil. All evil aligned creatures will receive a -2 penalty to their attack roll when targeting creatures protected by the spell, the protected creature receive +2 bonus to all saving throws from when targeted by evil creatures and also prevents creatures summoned by spells as Cacofiend, Summon Fiend and Gate.

Saving throws bonus
They gain +2 bonus to all saving throws.

Priest spells
Paladins are able to use priest spells when they reach lvl 9. They may only use spells levels 1 to 4. Any spells which effects are based on the casting level of the user, are limited for paladins between spell levels 1 and 9. Between lvl 9 and 20, the paladin will gain one spell slot each time he/she levels up.

Blackguard (Enhanced Edition Only)
The Blackguard epitomizes evil and is nothing short of a mortal fiend. The quintessential black knight, this villain carries a reputation of the foulest sort that is very well deserved. Consorting with demons and devils and serving dark deities, the Blackguard is hated and feared by all. Some people call these villains "anti-paladins" due to their completely evil nature.

Advantages: Disadvantages:
 * Immune to level drain and fear.
 * May turn undead as a Paladin of the same level.
 * May use the Absorb Health ability once per day, which deals 2 points of damage per level to an enemy and heals the Blackguard the same number of hitpoints.
 * May use the Poison Weapon ability once per day. Gains one use at level 1, one use at level 5, and an additional use every 5 levels thereafter. Each successful hit within the next round injects poison into the target, dealing an extra 2 points of extra damage per second with no Saving Throw (for a total of 12 points of damage). Moreover, if the target fails a Saving Throw versus Poison, he will suffer 1 additional point of damage per round for 4 rounds.
 * Aura of Despair ability (only for Dorn Il-Khan).
 * Blackguard status unaffected by reputation loss.
 * Alignment restricted to evil.
 * May not cast Detect Evil.
 * May not cast Protection From Evil as an innate ability.
 * May not use the Lay on Hands ability.

Blackguards also have a different minimum requirements than paladins:

Stronghold
Paladins receive a stronghold when they complete Rescue Gerran's Child from Firkraag.

Paladin Specific Items
Paladins have access to two of the best weapons in Baldur's Gate 2 as well as a special pair of bracers. One is a two-handed sword, Carsomyr the Holy Avenger, that obliterates evil monsters and can cast dispel magics. The other is a bastard sword called the Purifier. The Paladin's Bracers introduced in Watcher's Keep are a Paladin only item, and can be further upgraded to the Blessed Bracers making it one of the best hand-slot items in the game.

High-level class abilities
High-level class abilities are added in the expansion Baldur's Gate II: Throne of Bhaal. For all warrior classes and Monks, the pool of abilities can be accessed from the special abilities menu. These abilities are available to fighters when they nearing 3,000,000 xp. (exact lvl is not known).
 * Power Attack, this ability can be selected as many times you like.
 * Critical Strike, requires power attack. This ability can be selected as many times you like.
 * Smite, requires power attack and critical strike. This ability can be selected only one time.
 * Deathblow, this ability can be selected as many times you like.
 * Greater Deathblow, requires deathblow. This ability can be selected as many times you like.
 * Whirlwind, this ability can be selected as many times you like.
 * Greater Whirlwind, it requires whirlwind. This ability can be selected as many times you like.
 * Battle Cry, this ability can be selected as many times you like.
 * Hardiness, this ability can be selected as many times you like.
 * Resist Magic, this ability can be selected as many times you like.
 * Summon Deva (Paladin only)
 * Summon Fallen Deva (Blackguard only)