Wall of Lights

The Walls of Lights on the Serpent Isle are a connection to the Void, and to other places, planes and dimensions. It is not really explained how they actually work or what exactly they do. They were built by the Ophidians so that their highest priests could visit the three Serpents in the Void. They also enable others travel as long as the correct Serpent is used. One, or all of the Blackrock Serpents are needed to actually activate the Walls.

There exist three Walls of Light on the Serpent Isle, one for Order, one for Chaos and one for Balance, and they are each different to the other, having their own history, key and light effects.

Order
The Order Wall of Lights is found in Spinebreaker and can only be properly used with the Order Blackrock Serpent (it can be opened with the others, too, but walking through it won't work). The Wall is glowing blue and white. The forces of Order used it to leave the Serpent Isle after the War of Imbalance for an unknown place. In Ultima VII/2, Batlin wanted to go through it, but since the Soul Prisms were subjected to the energies emanating from it, they exploded, releasing the Banes. Guardian withdrew his protection from Batlin at that precise moment.

Chaos
The Chaos Wall of Lights is found in Skullcrusher and can only be properly used with the Chaos Blackrock Serpent (it can be opened with the others, too, but walking through it won't work). The Wall is glowing red and yellow. In Ultima VII/2, the Avatar used it to fuse the Chaos Serpent back together, returning it to the Void where it belonged to.

Balance
The Balance Wall of Lights is found in the Shrine of Balance and can only be activated with all three of the Blackrock Serpents. The Wall is glowing red, blue, yellow and white. In Ultima VII/2, the Avatar used it to return the Great Earth Serpent to the Void, where it belonged to.