Colored Aura/Smoke coming from tribesman

[Lag]

This morning i attacked the flint tribe, and one of the Tribesman i took back with me had a red aura, or red smoke emanating from him. I've seen a similar green aura before on a friends tribesman, does anyone know what this means? I can't seem to find anything specific.

[Vin]

green are usually the health regen passives they have. red is damage like damage increase of damage reflect or atk speed etc.