Sulzrirtas, sometimes called the Frigid Flame, is a demonic servant of Masvirik, the Cold Sun, imprisoned within a dusk shard after the historic conflict between Rhashaak and Masvirik.
Sulzrirtas' dusk shard was consumed by the Masvirik'uala Dax' Athla in 997 YK, allowing Sulzrirtas to possess the lizardfolk and go on a rampage across Q'barra. Several months later, Sulzrirtas was rebound by a priestess of the Silver Flame, but not before it was able to slaughter her.
Sulzrirtas remained dormant within Dax' Athla for some time after this, suppressed by the power of the Silver Flame and the protection granted by the priestess. It began to awaken once more when Dax' Athla visited Flamekeep and was exposed to the pillar of argent fire within.
Dax' Athla began communing with Sulzrirtas after this, in an attempt to exert control over the demon. This allowed Sulzrirtas to communicate with Dax' Athla.