Karnak is a member of the Inhuman race, one of those who form the Inhuman Royal Family, he has the ability to find the weak point in any person, plan, or object. Thus, he is usually used as the planner by the Inhumans. He also serves as a priest and philosopher to the Inhumans.
The Marvel Superhero Saga: In the City of Attilan
The Marvel Superhero Saga: W.A.R.R.I.O.R. Meeting the Inhuman Royal Family
The Marvel Superhero Saga: The Battle with Maximus the Mad