Hexen II/Bridge of Stars

The Bridge of Stars is the penultimate level of the hub, where placing all four elements in the place opens the path to the Well of Souls.

On the bridge over the lava, there is a Mystic Urn under the bridge itself. Reaching it will most likely require landing in the lava, as the platforms aren't easily visible from the bridge itself.

The fourth weapon's head is found on the other side of the bridge. If you missed the staff, it can bef ound in the Tomb of the High priest.

After the bridge is a set of platforms. Look for a teleporter to bring you to the topmost one, and touch the center pedestal on said platform. Descend each level, and place the element in the position.

When all four elements are placed, the path to the Well of Souls is unlocked. This is also the point of no return, thus you should finish desired activities in the hub before proceeding.