The Old World is a vast and untamed place where wild and monstrous creatures roam the dark forests and vast mountain ranges. There are many creatures roughly human in appearance, such as Orcs, Trolls, and Minotaurs, but there are also bigger and more bizarre monsters, such as Griffons, Dragons and Hydras.
It is with these monsters that this section of the rules is concerned. Monsters may be ridden to battle by mighty heroes and wizards. Many of these beasts must be hand reared by their master if they are ever to accept a rider, so the great leaders of the Old World pay vast sums to adventurers who collect eggs or hatchlings from the nests of Griffons and other winged monsters. This is a dangerous profession, and for many a fatal one, but it ensures that the Emperor's menagerie in Altdorf gains fresh creatures to rear on behalf of the nobles and wizard lords of the Empire.
Monsters are powerful elements of the army. Some monsters develop loyalty and devotion to their masters and will willingly fight for them, while others are placed under enchantments or simply driven forward towards the enemy in the hope that they will attack the right side.