The Kagrumez Trials requires you to collect four Kagrumez Resonance Gems, then travel to Kagrumez, kill the Reaver Lord for his gems and then solve the stone puzzles. These puzzles will unlock different trials that you need to survive.
After surviving the third floor you will have access to two friendly Dawrven creatures and the best bow in the game, the [ Dwarven Black Bow of Fate ] .
You only need a total of four to solve the puzzles, but there's five to be found in the game in total.
1). Found in Fahlbtharz
2). Found in the Nchardak Aqueduct, sitting on a table in the top north east room.
3). Sold by Revus Sarvani near Tel Mithryn
4 & 5). Carried by a Reaver Lord in Kagrumez .
Place a gem in each of the following holes in the pedestal (using compass directions as a reference point).
First Floor: West and South-East
Second Floor: North, South and South-East
Third Floor: North-West, Center, South-East and South-West