The Black Panther!
The FF are invited to visit the hidden land of Wakanda by their leader the Black Panther. While the FF travel to the African nation, in the Hidden Land, the Inhuman royal family try their best to break open the Negative Zone Barrier around their land, even Karnak's ability to find flaws in anything fails to break open the barrier.
Arriving in Wakanda, the FF and Wyatt Wingfoot are brought into the nations technological forest, and attacked by the Black Panther, who easily bests them all in individual combat, but is defeated when the FF team up as a group. With the battle over, the Black Panther states that it was all a test of their abilities, and now that they have won the "hunt" they deserve an answer as to why they were summoned to this land.
(From Marvel DataBase)