Mount Prism is a holy sanctuary where the divine dragon, Naga resides in Awakening. If the Falchion is brought here with the Fire Emblem, one can perform the Awakening Ceremony, unlocking the true power of the Falchion. However one must be deemed worthy by bathing in Naga's holy flames. Should their inner fire not burn hotter than the flame, that person will die. In Chapter 24, Chrom comes here to complete the Awakening Ceremony, after being advised by Frederick. However, when they arrive at the summit, they find a group of Risen lurking around, but after a short battle, eventually kill them all and proceed into the sanctuary.
On the mount's peak there is a large waterfall and several scattered ruins among a forested area.
Mount Prism is mentioned in The Future Past DLC, where in this timeline, Chrom was killed by the possessed Robin. Tiki had moved to Mount Prism, and needing protection, Lucina (being the current exalt), sent a group of Ylisseans to protect her. Grima sent hordes of Risen to kill Tiki, aware of her powers. The Risen eventually overwhelmed the Ylisseans and desecrated Mount Prism; however, Tiki was able to escape with the help of the remaining survivors, who sacrificed their lives for her. The actions of the Risen moved the divine energy of Naga into the next holy place, which was Tiki.
- Mount Prism appears to be located in what used to be Western Talys, in the mountain range near Talys Castle.