Codex: Chaos Space Marines (1999), p20 — Wargear

Spiky Bits: Chaos Space Marines often add ornate and fearsome spikes to their armour. Why they do so, no one is sure, though some say it may be in praise of the minor Chaos powers Mo'rcck, Phraz-Etar and An'sl. Whatever the reason, a Chaos Space Marine adorned with spiky bits may re-roll one close combat To Hit dice per assault phase.