The Messengers of Thirteen were sent to Mordheim by the leader of Clan Eshin to capture as much of the wyrdstone as possible, so that it could be used for their evil deeds. They came from the captured Dwarf Stronghold of Karak-Varn, which the Skaven had taken nearly two millennia earlier.
The intial warband sent to Mordheim was rewarded with thirteen members, the number of the Horned Rat. Pzaap, the Eshin Sorceror, had been made the advisor and captain of the pack by the Lord of Karak-Varn. As a sorcerer, he had enough intelligence to make tactical plans and strategies. Quirik, being an Assassin, was the leader of the pack as far as the other Skaven were concerned, as it was always seen that Assassins were the real leader.
Quirik was accompanied by his friend and comrade, the Black Skaven Skrat. They had often fought together, both in combat and in training fights. Each had many minor scars from where their training fights had got out of hand. Quirik knew he could rely on Skrat to fight by his side and capture the wyrdstone.
Pzaap also requested the help of two Night Runners. Pzaap knew that these apprentice Gutter Runners would prove useful in the crowded, narrow and dark streets of Mordheim. Eventually, Darc and Ligit were assigned to the pack. They each specialised in different areas of the Gutter Runner's skills. Darc was a slinger, who was an expert at stealth ranged killing. Ligit looked as if he would become an Assassin, prefering to use his stealth to sneak up on the enemy and disembowel them while they weren't looking.
To give the pack an advantage in numbers, they were also accompanied by two packs of verminkin. The first pack was three of Quirik's apprentices. They were training in the same field as Darc, the art of stealth ranged killing. They were known only as "Quirik's Slings", and Quirik hoped they would provide covering fire for him to attack under.
The second pack was chosen by Pzaap. Being a wizard, he needed a bodyguard, and so chose five of Karak-Varn's best fighters. These five verminkin became known as "The Sword's of Thirteen". They have sworn an oath to protect Pzaap, and will be devoured by the Horned Rat himself should they fail.
Once in Mordheim, the Messengers of Thirteen often encountered the Reiklanders, "Freizmans Mercenaries". In many conflicts, the Messengers came out on top, often managing to grab most of the precious wyrdstone.
Due to their excellent progress in the City of the Damned, the Messengers of Thirteen were twice rewarded by the Lord of Karak-Varn. The first reward was the appointment of Skritt into the pack. Skritt was another Black Skaven who had recently proved himself worthy of joining the Messengers by killing three other Black Skaven in unarmed combat. The second reward was even greater. Quirik hadd been granted one of Clan Mulder's prized Rat-Ogres. This beast, known only as Raar, would strike fear into the hearts of even the most hardy of warriors, only moments before tearing them apart.
The Messengers of Thirteen were now a renowned pack in the North-western sector of Mordheim. The thought of fighting against an assassin, his two Black Skaven, a sorceror and his pet Rat-Ogre was enough to strike terror into the hearts of all leaders in the area.