Kasimir met the first group aligned with these goals in Curse Of Strahd, when the camp was visited by foreign adventurers called Pack. He told them of his people's history as well as some of the Barovian Calender Timeline, and learned that the group was interested in the Amber Temple. Kasimir pleaded with them to take him if they were to ever make a mission to the temple, which they were unsure of, but agreed tentatively to.
An Elven Wizard hailing from the Svalich Woods of the Zarovich Valley, Kasimir Morvaris was raised as a typical elven mage. Raised in the shadow of his talented older sister, Patrina Morvaris, he was taught deep arcane secrets while living in tune with the forest. His life was uprooted into one of war when the von Zarovich family began to reattempt a conquest of the valley, and various houses leaned on the wood elves to assist in their fights using guerilla warfare. This impeded the efforts of Barov von Zarovich, who convinced one of their own, Rahadin, to kill the elven leaders.
Already low in number, his people were on the verge of annihilation by Strahd von Zarovich's armies when they surrendered. Strahd forbid the elves from returning to the forests, and forced them to break off contact with any of his enemies; the remaining elves were left to the "mercy" of the Vistani, who kept a watchful eye on them at the Vistani Camp west of Vallaki. Kasimir eventually adopted a new surname by an old Vistana named Velikov long ago, a good man who had welcomed him into the clan. The two eventually became close, and Velikov gave Kasimir his Ring of Warmth as s show of affinity and brotherhood.
Though Vistani typically did not keep surnames, Kasimir continued the Barovian tradition of keeping his name as legacy, out of respect for Velikov's kindness. When the Vistana was killed by the Captain Zandros, Kasimir continued to live among his descendants. In his view, however, the modern Vistani were not as noble nor as enlightened as their forebears. Not one to press the issue, he hoped to simply outlive the leadership of Luvash and Arrigal to see a return to the old ways.
After Strahd turned Barovia into a mist-ridden demiplane, the elves began to think of him as the ultimate evil, and suspected that Kasimir's older sister Patrina was his concubine. Kasimir grew increasingly convinced of this, and convinced Patrina to speak with honesty to their elders. Horrified at what Patrina had become, the elves magically bound her, and forced her to admit her misdeeds; among them, she had killed an elven child and bathed in his blood as part of a necromantic ritual. With their fears confirmed , the elves stoned her to death in rage to thwart Strahd's plans.
This act would result in the Dusk Elf Massacre. As punishment for depriving him of his bride, Strahd butchered all the women in the wood elf tribe. Rahadin cut off Kasimir's ears and scarred his face. Mutilated and grief-stricken, he began to wear a cowl to hide his humiliation, though remained the leader of the remnants of his people. Many years after her stoning, Patrina spoke to Kasimir in dreams, telling him how years of guilt and regret have dispelled all evil thoughts from her mind, cleansing her tortured soul. However, Kasimir remained unconvinced by these assertions, because he knew that Strahd had corrupted Patrina. She told Kasimir that the Amber Temple, an ancient vault hidden in Mount Ghakis, was where Strahd forged his pact with evil powers and discovered how to become a vampire.
Kasimir believed that the secret to breaking Strahd's pact and freeing Barovia was in the temple, but more importantly, believed that the temple held the secret to bringing his sister back to life. Using Velikov's ring, he traveled to the temple and spied on it, but determined it to be too dangerous to enter without extremely capable backup.