From wow.incgamers.com

Background

One of the 6 Horde races: Orcs, Tauren, Undead, Trolls, Blood Elves and upcoming Goblins.

Age old enemies of the Night Elves. The forest trolls of Lordaeron tried to take The Kingdom of Quel'thalas from the High Elves but failed because the Human Empire of Arathor aided them. Joined the Warchief Orgrim Doomhammer in his war against the humans in the First War.

The Frostmane Trolls once rules over the frigid lands of Dun Morogh, only to have their empire fall to Dwarven armies. These tribal creatures were driven to the hills in retreat; a shameful blow to their warring nature. With King Magni Bronzebeard's forces split between the Alliance Wars and quelling the Trogg invasion, the Frostmane Trolls have seized the opportunity to reclaim Dun Morogh in an attempt to restore the kingdom that crumbled under Dwarven might ages ago.

The vicious Jungle Trolls, who populate the numerous islands of the South Seas, are renowned for their cruelty and dark mysticism. Barbarous and superstitious, the wily Trolls carry a seething hatred for all other races.

One tribe, however, was forced to overcome its prejudices when it encountered the Orc Warchief, Thrall, and his mighty Horde. The Trolls of the Darkspear Tribe, long since exiled from their ancestral lands in Stranglethorn Vale, were nearly destroyed by a band of aquatic Murlocs, but Thrall and the Horde managed to save them. In return the grateful Trolls swore an oath of eternal allegiance to the Horde.

Led by the cunning Shadow Hunter, Vol'jin, the Darkspear Trolls now make their home in Durotar along with their Orcish allies. Their village, named after their fallen tribal elder, Sen'jin, lies along the eastern coast of the harsh, rocky land. The Darkspear Tribe also occupies tracts within the nearby jungles of the Echo Isles.

As part of the Horde, the Trolls have extended their loyalty to the mighty Tauren, but they have little trust for the manipulative Forsaken, whom they believe will visit only misery and strife upon their allies. - Blizzard

The Darkspear Trolls

In World of Warcraft the player can play as a member of the Darkspear troll clan. Trolls don't have a capital of their own, they share their hometown (Orgrimmar) and starting zone (the Valley of Trials) with the Orcs. The clan is lead by Vol'jin, who can be found in Thrall's chambers in Orgrimmar.

Classes

The trolls have six classes to choose from:

• Hunter
  
• Mage
  
• Priest
  
• Rogue
  
• Shaman
  
• Warrior
  

Racials

All troll characters get the following racial abilities:

• Berserking: Activate to increase attack and casting speed for 10 seconds. Speed is raised by 10% at full health, increasing as health is lost to a maximum bonus of 30%. 3 minute cooldown.
• Regeneration: Increase health regeneration bonus by 10%. Also allows 10% of normal health regen during combat. (Passive)
• Beast Slaying: 5% damage bonus to Beasts. (Passive)
• Throwing weapon specialization: Increase Throwing Weapon skill by 5. (Passive)
• Bow specialization: Increase Bow skill by 5. (Passive)

In addition, troll priests will get the following racial skills:

• Hex of Weakness: Weakens the target enemy, reducing damage caused by 2 (35 @ lvl70) and reducing the effectiveness of any healing by 20%. Lasts 2 min.
• Shadowguard: The caster is surrounded by shadows. When a spell, melee or ranged attack hits the caster, the attacker will be struck for 20 (130 @ lvl68) Shadow damage. Attackers can only be damaged once every few seconds. This damage causes no threat. 3 charges. Lasts 10 min.

Additional info

The Darkspear Trolls have given up cannibalism as a part of their pact with Thrall and the rest of the Horde races.