Does this ability stack?

Ie if I have Nazdreg at a planet and an Enraged Ork, does the ork gain +2 ATK per damage?

No it does not. If it was to stack it would say Brutal (1) or Brutal (2).

Thanks for the quick reply.

The section on keywords in the RRG, p. 9, explains this in detail. The shorthand version is:

- Keywords (like "Brutal") do not stack. You either have it or you don't. So Brutal + Brutal = Brutal.

- Numerical values following Keywords will add together, though. So Area Effect (1) + Area Effect (1) = Area Effect (2).

Ahh yes I see it now. A case of wanting to get into the action without properly reading the rules