The model is gifted with a mighty Axe of Khorne, suffused with chaotic power and laden with death! A hit from the Axe of Khorne ignores armour saves. In addition, any to hit rolls of 6 allow the model to make an additional attack in close combat. As long as you keep on rolling 6s you can keep on making additional attacks. These additional attacks may be allocated against new opponents if desired.
Axe of Khorne
Source: Codex: Chaos Space Marines (1999), p. 28