How exactly does Shadower Instinct work?

It says for example +30 atk buff duration plus 6 from Body Kill Count.
Does that mean that +30 atk + (6x30atk)
Or
+30 atk + 6 atk?
Or does the body kill count works entirely different?
This is kinda confusing

 No Shadower Instinct

 Shadower Instinct with full Body Counts

You get 6 more attack for every body count point you have, for a maximum of an additional 30atk (60atk total at max).

Ah, ty.