Codex: Chaos Daemons (2018), p125 — Daemonic Loci

Nurgle: Locus of Virulence

The Daemons of Nurgle are surrounded by an aura of pestilence and disease that infects all nearby, and their talons and blades drip with thrice-ripened plagues. The merest touch of such a weapon in the presence of such a creature can cause a mortal to wither and die in seconds.

Each time you make a wound roll of 6+ for a NURGLE DAEMON unit within 6" of any friendly model with the Locus of Virulence, that attack inflicts 1 additional damage.