In Curse Of Strahd, the monster slayer Ezmerelda D'Avenir came to Vladimir at Gofrey's behest, looking to take the Holy Symbol of Ravenkind. He and his Phantom Warriors slew her where she stood, though unknown to Vladimir, Godfrey kept her body alive with a Spell of undead stasis.
Raised in a Human Barbarian tribe that hunted around the Everglass close to the Sea of Clouds, Vladimir Horngaard was an uncommonly strong, stern, and dedicated Fighter. By chance, as he and his clan were conducting a raid of another tribe, Vladimir encountered the Silver Dragon Argynvost disguised in Human form. Finding that he needed further purpose than simple subsistence, Vladimir joined the Order of the Silver Dragon and quickly earned the trust and respect of Argynvost. Vladimir swore a vow to Argynvost, and became a paladin of his Order.
Vladimir possessed remarkable natural talent with both sword and will, and quickly became the most powerful knight in the Order besides Argynvost himself. He was eventually relocated to the Silver Dragon's Hideout, where he met the inductee Godfrey Gwilym. Though of extremely different backgrounds, the two men found that the balanced out the others foibles, and they quickly fell in love. Alongside Godfrey, he battled for the forces of light against the myriad threats of the Underdark; during a defense of the hideout, he became good friends with the Dark Gnome Irsel Rill Lakerun Gembop Geoheart, as described in Captain Horngaard's Journal. Vladimir was eventually promoted to the role of Captain, with Godfrey his steward. Alongside the title, he was gifted the Order's rarest possession: a Greater Enhanced greatsword with a hilt sculpted to resemble silver dragon wings and a pommel shaped like a silver dragon's head, clutching a black opal between its teeth.
Argynvost's true purpose for the Order, hidden from its members, was to investigate the Azure Paragon and find out its secrets. This search led him to the Zarovich Valley, where a warlord named Strahd von Zarovich had begun terrorizing the region. He elected to defend its innocents against the would-be tyrant, and brought Vladimir along to construct Argynvostholt, a fortified mansion in the heart of the valley. Godfrey refused to allow his lover to leave without him, and the two found themselves fighting Strahd's armies time and time again as they swept across Barovia. The knights experienced many early successes, notably in the Rout Of Barovia where Horngaard slayed Barov von Zarovich and Ravenovia van Roeyen, but these victories dwindled over time.
After the Wedding That Never Was, it became clear that Strahd could not be stopped, the knights of the Order led hundreds of refugees to Argynovst's valley, but Strahd tracked them to their sanctuary and overwhelmed them in the Attack On Argynvostholt. Vladimir witnessed Strahd slay Godfrey before his own eyes, and could not hold back the evil tide himself. With the battle won, Strahd surrounded Argynvostholt, and his forces eventually dragged down and killed Vladimir. Rather than cower in his lair, Argynvost emerged and battled Strahd's armies to the bitter end.
Unwilling to accept his failure, Vladimir returned as a Revenant. So great was his hatred of Strahd and his thirst for vengeance that those feelings fueled the spirits of many of his fellow knights to come back as revenants as well. Vladimir continued to wage the hopeless war, even as Strahd tightened his grip on the valley, and was continually rebuffed with little effort. Due to the Vampire's pact with the Dark Power Vampyr, the knights spirits were trapped behind curtains of mist. Over centuries, he became a hate-filled shell of his former self, and forgot most details of his life; even his love for Godfrey became a dim memory.
He became convinced that all of the valley had been swept into "hell" and that Strahd was living in his own personal eternal torment. Consumed by hatred, he consigned the fate of himself and his retinue so long as Strahd suffered. As such, he sought to destroy any who looked to defeat Strahd, often killing the few brave Barovians and well-intentioned adventurers looking to save Barovia. One such group possessed the Holy Symbol of Ravenkind; after he slew them, he began to guard the Symbol intently as he knew it was a tool that could defeat the vampire.
At some point, the swamp witch Baba Lysaga of Berez attacked Agynovstholt with her covern, as well as a host of Scarecrows. The old woman thought that its standing was an insult to Strahd, and wished to take it back from the dead paladin order. An overwhelming number of her Constructs began disassembling the mansion's southern wall, but she and her forces were eventually beaten back by the revenant knights at Vladimir's command.