Locus

While this model is leading a unit, models in that unit have the Fights First ability

While this model is leading a unit, other Character models attached to that unit have the Feel No Pain 4+ ability

This model can be attached to the following units: - Acolyte Hybrids - Hybrid Metamorphs - Neophyte Hybrids You can attach this model to an Acolyte Hybrids or Neophyte Hybrids unit, even if a Primus, Magus, or Acolyte Iconward model has already been attached to it. If you do, and that Bodyguard unit is destroyed, the Leader units attached to it become separate units, with their original Starting Strengths.

Each time this unit makes an ingress move (20.04), if every model in this unit has this ability, it can be set up anywhere on the battlefield that is more than 8" horizontally from all enemy units, even if that is within your opponent’s deployment zone.

While every model in a unit has this ability, that unit is a Fights First unit.  See the Resolve Fights First Combats step in the Fight phase (12.04).