A quick search in UESP brings up
Diagna, Orichalc God of the Sideways Blade
Hoary thuggish cult of the Redguards who originated in Yokuda during the Twenty Seven Snake Folk Slaughter. Diagna was an avatar of the HoonDing (the Yokudan God of Make Way) that achieved permanence. He was instrumental to the defeat of the Lefthanded Elves, as he brought orichalc weapons to the Yokudan people to win the fight. In Tamriel, he led a very tight knit group of followers against the Orcs of Orsinium during the height of their ancient power, but then faded into obscurity. He is now little more than a local power spirit of the Dragontail Mountains.
but no orichalc tower though the intercept mentions it.
So we have these towers that have fallen:
Red Mountain
Walk-Brass [Anumidium]
White-Gold Tower
Orichalc??? (the god associated with it is now a local power spirit after maybe using the tower or stone within to create weapons to destroy the Left hand elves?? ( i dont really know what to do with it)
So the remaining ones are:
Crystal-like-Law [The Crystal Tower]
Green-Sap [Falinesti]
Snow Throat [Throat of the World
Crystal Tower is in Summerset, Green Sap in Valenwood and Snow Throat in Skyrim where we are next headed. So perhaps it is time for snow throat to be destroyed as well making this world even more unstable ?
I don't know what is happening to the Crystal Tower and Green Sap or indeed the Orichalc, if anyone has read anything then do let us know.
The thought of the Redguards fighting the left hand elves using weapons built by destroying the orichalc tower appeals to me. Since the tower was gone and its influence on creation extinguised this could have caused Yokuda to sink and disappear. So in effect the Redguards brought upon them the destruction of their homeland and had to move to Tamrie:l the centre of the eternal struggle of men and mer. Of course this is all conjecture