From 'The Last Enemy' Game.
There was a fourth reflection of the Primal Pattern in the Amberverse of The Last Enemy game. Although it is long since destroyed as a Pattern it is known as Ht'gon An-Rit (the reverse of Tir-Na Nog'th, as Rebma is the reverse of Amber). According to Brand it is not an elemental reflection of the Primal Pattern (that is, the Patterns of Amber, Rebma, Tir-Na Nog'th and Ht'gon An-Rit are not reflections based in Earth, Water, Air and Fire respectively).
Julian knows of the place, which is in a hard to reach mountainous area of Forest Arden. It is as far from Amber as the Rebman Pattern is, in exactly the opposite direction, roughly twenty miles north of Amber city and somewhat inland. It is also as far above Amber as the Rebman Pattern is below.
Julian keeps the place guarded by a detachment of Rangers. According to him Oberon and Caine also knew of it (of those from the Amber side of the universe). Oberon told him about the place and set him to guard it. He claims that he tried to find out more about it, but could not, and that since it was dead and gone long ago there seemed no point in mentioning it. His daughters did not know of it. He has a Trump of close to it in Arden, a location which is guarded by hidden Arden Rangers with crossbows.
Up the slope of a hill from the Trumping-in point one travels along a path through steep woods which could almost be an old staircase. This passes uphill through trees and tree-covered rock formations like fossilised buildings (though it is clear that they have never actually been buildings). Apes can be seen and heard in the trees and on the rocks; they seem rather shy. On top of the hill is a shallow oval bowl-shaped clearing easily large enough to contain a Pattern, surrounded by a low wall (about two feet tall) and with tall trees overhanging it. It feels Real there, similar to being in the Pattern Room in Amber.
The area from about ten feet inside the wall is a blackened and burned oval the size of a Pattern (roughly one hundred by one hundred and fifty yards in extent) but showing no signs of its former design. The whole thing feels like a Pattern, but wrong, destroyed. According to Julian there is still power there, enough to kill things in the same way as the intact Patterns. The wall is a safety precaution to stop people wandering onto it.
When the sun comes out the sunlight seems to fall through the leaves of the overhanging trees in such a way as to form the shape of a Pattern on the blackened space, different to those of Amber, Rebma or Tir-Na Nog'th. The whole place feels more Pattern-like when this happens. That is, the Ht'gon An-Rit Pattern was apparently an ephemeral one, like the Pattern in Tir-Na Nog'th, only appearing under the right conditions when sunlight and shade, shining through the leaves of the trees which grow there, created a greenish-gold Pattern on the grass of the clearing. Obviously being on the Pattern if the sun went in would have had as bad consequences as having the Moon go in when walking the Tir-na Nog'th Pattern...
It seems that it was destroyed by blood, the damage having destroyed the structure, but not the power which lay behind it (in the same way as the damaged parts of the Primal Pattern still had power, even if only to destroy).
In the trees at one end of the Ht'gon An-Rit Pattern, outside the wall, are two small rock-cut pyramids, twenty feet tall, carved from the local rock. From the outside they are featureless and bear no identifying marks other than a door-less opening into the interior with the unicorn of Amber carved into the stone above it. The opening faces out onto the Pattern. Inside each one is a single unadorned chamber, in the centre of which is a large stone sarcophagus with the Unicorn of Amber carved on the lid.
In one sarcophagus is the skeleton of a seven feet tall ape-creature with large hands and long, clawed fingers, much bigger than the apes living in the trees outside. It wears shreds of male court clothing in a very old style.
In the other tomb is an un-decayed female human figure, young-looking, elfin, with a slight build and a distinct resemblance to Oberon (hard as that may be to imagine!). Her neck appears to be broken, and bears bruising the form of which matches the hands of the ape-creature. She is wearing a long court dress (again in a very old style) and some jewellery in the same style as the Crown Jewels of Amber. Her hair is darkish red (the same colour as Oberon's).
Julian had no idea who either of the bodies was, but according to Benedict the woman was named Morgana, and the ape-creature was a part of his younger brother Finndo, who died as he killed her (Finndo was a shapeshifter with an ability to sub-divide himself). She objected to her Pattern being destroyed, as Oberon had ordered Finndo to do, and both died in the fight which ensued...