Chornyi Oprichnik: The Black Dogs Seeping Out of My Dreams (我が夢路に這い出よ黒犬, Waga Yumeji ni Hai Deyo Kuro Inu?) is a Noble Phantasm transformed from the Thunderous Emperor's Extraordinary Authority, based on his "royal guards (the Oprichniki)".
The Oprichniki were an existence that you could call the hands and feet of the Thunderous Emperor Ivan and they held the authority to seize the property and lands of every noble. Fully clad in black cloths, they rode on black horses using black harnesses. Said horses had the head of a dog hanging from their necks while their riders held broom-shaped whips knits from animal hair in their hands. "Rebels will be struck down like a dog and swept out with a broom", the dog heads and the brooms seemed to imply such a thing.
Their brotherhood whose members once ate, slept and lived under the same roof, does not exist in this world anymore; their only traces left are the beings creeping in the dreams of Demonic Beast Thunderous Emperor Ivan. A Noble Phantasm that activates on its own once the Tsar has fallen asleep, protecting and ruling over his dominion. The Noble Phantasm spawns an infinite number of soldiers, who do not rest until the enemy is killed. As a group, their might is overwhelming; the individual soldiers' relatively low strength being its only weakness. However, in the vicinity of the capital city, Moscow, even a single unit has power comparable to a low-rank Servant.