Hexen II/Tomb of the High Priest

The first room has several enemies, including a few archers on the upper section. There is also a piece of your fourth weapon in the middle. The upper floor leads to a secret area, accessed by striking the mural on the side opposite the archer platform. This secret contains a werepanther guarding a Seal of the Ovinomancer.

When you head downstairs, you will encounter more enemies. This is mostly a single path, with a skull wizard facing a tome of power. Continue along the path, and a wall should open to another set of downstairs. There's two crushing wall traps as you head down, recognized by the wall murals, and evaded by slowing down as you approach them.

The large chamber will have a skull wizard and two werejaguars. Approaching the sarcophagus near the wizard will reveal a mystic urn after it opens.

The side opposite the sarcophagus leads to the element of air. You can also use a nearby teleporter as a shortcut back.

This is all to be done here. You can head to the Court of 1000 Warriors for the element of earth, or continue to the Bridge of Stars. If you want the other piece of the fourth weapon, it also can be found at the Bridge of Stars.