Just as the Warhammer World is riven with internal strife so the Realm of Chaos is partitioned between rival powers. Daemons of different kinds vie with each other for supremacy and for the favours of the great powers of Chaos - the Chaos gods themselves. The different kinds of daemon are strongly aligned to one of these gods, Khorne the Blood God and master of battles, Tzeentch the Lord of Sorcerers, Nurgle the Plague Lord, and
Slaanesh the Prince of Chaos.

If a Chaos army includes daemons of two or more Chaos gods then you must take into account the rivalry between them. This can mean that your troops will sometimes attack each other rather than the enemy. This is called Daemon Animosity.

If you have daemons of different Chaos gods within 12" at the start of your turn, and they are not already engaged in combat, you must make a Daemon Animosity test to see what they do. Roll a D6 for each unit of daemons or each individual Greater Daemon model.

Note that daemon steeds, familiars and such like do not suffer from Daemon Animosity as described. Only Greater Daemons and demonic units are obliged to test. Also, bear in mind that daemons engaged in hand-to-hand combat do not need to test, although they may still be attacked by rivals who do. Daemons already fighting each other due to the effects of Daemon Animosity do not have to test further as they are already affected.