Casildo Imam was a geologist working in a ravine north of the Rinzeremel Mountains at the edge of the Muioqa Desert on the day of The Cataclysm. The ravine saved him from the initial blast, but the seismic shock opened up the ground beneath him creating a chasm nthat widened almost contantly for weeks with seismic activity. Such activity is recorded by a journal kept by Casildo as well as records kept by the Pewamro who were also caught in the chasm. While these individuals were spared death in the initial blast, the radiation and fallout from the blast tainted water and began making changes to their DNA. These changes resulted in rapid mutations, particularly after a wound had healed. Over time, the mutations were such that survivors were misshapen, with skin ranging from flaky and dry to having a leathery or reptilian appearance. Those who survived the blast also had to manage their resources very carefully, working through the The 30-Year Winter and its cold on the surface and avoiding the roiling lava flow at the bottom of the chasm. Casildo wrote this letter to his wife as a farewell. It is unlikely she survived the initial blast.
The letter was given to one of the Pewamro by Casildo before he died. He asked them to hold onto it until they saw someone from the surface. The promised him to do so, and the letter remained in their possession until nearly 700 years later. At that time, explorers from the surface came upon the chasm by accident. The Pewamro gave the explorers the letter, although by this time its history was lost to them. The letter was returned to Orsholon City, and is now kept in the Royal Archives. Occasionally, it is brought out for the Festival of Tonoos, in remembrance of those who perished in The Cataclysm.
Most see the letter as a last outreach from a husband to his wife, a missive written to express his grief and fears, and his longing to be with her. Of course, there are the cynics who point out that if he had stayed home, he would not have ended up in the chasm, but this is usually discounted as unnecessary cynicism, as he would also have perished with her.