"Mountaintwain" was the colloquial name for a large mountain, but was also called "Scyseti's Cut", "Splitrock", and the "Half-Mountains" to various groups in the region. The mountain was located at the eastern edge of the Snoutridge Mountains, leading into Phalor-Phaeun; its rise dwarfed all other mountains in the region, becoming an easily identifiable symbol for navigators. Prior to its sundering, the mountain housed many prosperous mines and was key to many local economies. The claims to these mines were held by Commoners, Scycaens, as well as s from the Kingdom of the Twelve Mountains. However, they were thought to be unstable after the rock was split, and all official activities in the mountains were suspended.
The largest mountain at the southern end of Sycae-Scyceti, it was famously cleaved by Riyissan Terrescel's magical sword Scyseti in the Battle Of Sylphglade. Soon after, the armies pushing north retreated, and the mountain stood a symbol of the Scycaen threat thereafter.