The Children of the Horned Rat worship disease, poison, death, and conquest. Nowhere is this more evident than among skaven monks and priests. These skaven deliberately expose themselves to disease, and view spreading disease as an act of praise to the Horned Rat. At the lowest level, the plague monks spread the Horned Rat’s doctrines, encouraging clanrats’ faithfulness and identifying those whose fervor lacks sufficient passion. At the top, a grey seer oversees the several clans in the horde. Gifted with potent magical powers, a grey seer receives visions from the Horned Rat itself, and then interprets those visions in order to direct the horde’s unceasing activities aimed at conquest.
Throughout the hierarchies of skaven society, betrayal and murder are frequent methods of advancement. For example, few plague monks advance to the rank of censer-bearer by hard work and devotion to the cause alone, and more than one skaven warlord attained that rank by orchestrating the death of the previous warlord. All of this is encouraged by the doctrines of the Horned Rat, and even a grey seer lives both fearlessly and fearfully, motivated by burning zeal for the Horned Rat while always alert for that ambitious underling who plots the current grey seer’s demise.
Armor Class: 7 
Hit Dice: 1+1
Special: Disease (15%), zeal (+1)
Clanrats who exhibit special zeal for the Horned Rat are tested for suitability to serve as plague monks. Those that fail this test die, which itself is considered an act of devotion. Plague monks are given special training that instills in them supernatural zeal for the Horned Rat. This zeal grants a +1 bonus to saving throws against poison and disease. It also infects many plague monks with horrible diseases, the marks of which are viewed as badges of honor. Plague monks rub their weapons in filth and against their oozing sores. Those damaged by a plague monk’s weapon may contract some ghastly sickness.
Armor Class: 6 
Hit Dice: 2+1
Attacks: Weapon (1d6+1)
Special: Disease (20%), plague-censer, zeal (+1)
The best, most zealous, most murderous plague monks become plague censer-bearers, and they undergo rigorous training with one of the skaven’s most feared weapons. Most trainees die before graduation, killed by the very weapon they seek to master. The hardiest monks survive, and they become more infectious, driven by fanatical love of the Horned Rat. A plague censer is both a flail-like weapon and a religious tool. Before battle, the plague censer is filled with noxious substances such as rags soaked with the effluvia of disease. The censer-bearer lights these substances, which smoulder and smoke. Wielded in combat, the plague censer fills a 10-foot radius around the bearer with disease-causing smoke. All caught in the radius (including the bearer) must make a saving throw. Failure causes 1d6-1 points of damage from blisters and buboes as blood and pus fills the victim’s lungs. This damage continues each round until death occurs or appropriate magic is used to counteract the effects.
Armor Class: 5 
Hit Dice: 4+1
Special: Breath weapon, disease (25%), spells, zeal (+2)
Plague censer-bearers who survive long enough may rise further in the ranks of the Horned Rat’s clergy and become plague priests. All plague priests cast spells as 4th-level Clerics, but they can never cast spells that heal or cure. Once per day, a plague priest may belch forth a foul cloud of sickness that fills a 20-foot radius around the priest. All caught in the area, including skaven, must make saving throws are else suffer the same effects caused by a plague censer. Ferocious ecstasy fills any skaven who succumbs to this horrible power. These skaven fight with a +2 bonus on attack rolls until they die from the disease.
Armor Class: 5 
Hit Dice: 8+1
Special: Breath weapon, disease (30%), spells, zeal (+3)
The grey seer is the mightiest skaven in any tribe. Its mere presence on the field of battle inspires maniacal bloodlust in all skaven within 60 feet who can see and/or hear it. Affected skaven cause +1 damage with their attacks, and they are immune to fear and sleep. A grey seer casts spells as a 4th-level Cleric and a 4th-level Magic-User, but its spells can never heal or cure. Once per day, a grey seer may cause the ground to crack open for pour forth 20-80 giant rats. These giant rats are always diseased, and they attack the grey seer’s enemies until destroyed or driven away.