Stormvermin, Warpfire Thrower, and Ratling Gun tear through a regiment of Empire Halberdiers.

The Skaven are a race of malevolent rat-men that inhabit the underground of the Warhammer world. The tunnels of their vast under-empire reach from the steaming jungles of the Southlands to the snow-covered steppes of Kislev, from the western borders of Estalia and Bretonnia to the lost realms of the Far East. Their capital is the mysterious city of Skavenblight, hidden in the centre of the foul marshes lying on the western borders of Tilea. There, the mighty Lords of Decay, ruthless rulers of all Skaven, sit on the Council of Thirteen, scheming and preparing for the time when their armies will emerge from the subterranean realm to raze the entire surface of the world. Such is the ultimate ambition of the Skaven race, a destiny preached by the Grey Seers, who are powerful Wizards and prophets of the Horned Rat, the malevolent Skaven deity.

Skaven society is structured into a number of clans that constantly vie with each other for dominance, and their political system is dominated by endless treachery. In addition to the Warlord clans, which supply Clanrat Warriors, Stormvermin, Clanrat Slaves, and Rat Swarms, there are four major clans that contribute troops to the Skaven horde: Clans Pestilens, Eshin, Moulder, and Skryre.

Clan Pestilens, as the name implies, aims to spread disease throughout the world. Led by Plague Priests, the troops of Clan Pestilens include the Frenzied Plague Monks, Plague Censer Bearers, and Plague Rat Swarms, which attack the enemy with diseased, Poisoned Attacks.

Clan Eshin disappeared from the Skaven society of the Old World many centuries ago and was considered lost. Eventually, its members returned to Skavenblight, though many of their habits had changed. Clan Eshin had traveled widely, learned much in distant lands like Inja, Cathay, and Nippon, and perfected the art of silent and stealthy warfare. As such, Clan Eshin provides Assassins as well as light skirmishing troops and infiltrators called Night Runners and Gutter Runners to the Skaven horde.

The members of Clan Moulder are animal trainers who experiment with radical, and often Chaos-influenced, crossbreeds between the creatures they capture. Master Moulders and Packmasters lead units of Giant Rats and hideous Rat Ogres into combat.

Finally, Clan Skryre is the most experimental and intellectually advanced group of Skaven. Members of the Clan specialize in the blending of evil magic and arcane Skaven technology. The Clan’s Warlock Engineers have developed several types of ranged weapons that can have a devastating effect on the enemy: Warplock Jezzails, Poisoned Wind Globes, Ratling Guns, Warpfire Throwers, and the dreaded Warp-Lightning Cannon.

These troops are led to battle by Grey Seers, who sometimes bring Screaming Bells, giant magical bells pushed forward by the Skaven horde, and by Skaven Warlords who are the most powerful fighters in the Skaven army. These leaders have many different types of weapons and troops at their disposal and must coordinate them in well timed attacks. Though the Skaven are numerous and almost always outnumber their foes in battle, they are, by and large, weak and undisciplined. Only when they have sufficient numbers do they have the nerve to enter into protracted combats, and only when they can bring their huge numbers to bear can they bring down the enemy. However, as many a commander who has watched his men fall to the teeming numbers of the Skaven horde can attest, the rat-men are formidable foes and can destroy even the most battle-hardened veterans by sheer weight of numbers.