Atmospheric folk horror book cover. In the foreground, a dark, eerie northern Karelian forest with ancient twisted pine trees, thick mist rising from a dark peat bog, and bioluminescent emerald-green moss glowing faintly on gnarled roots. In the middle ground, the silhouette of an ominous wooden pagan idol or twisted tree trunk resembling an open maw hidden among the trees. Dark, moody, cinematic lighting, cold blue and damp moss-green color palette with subtle glowing emerald accents. Cinematic composition suitable for a book cover with negative space for typography. Crisp typography at the top or center reads the Russian title 'ГНИЛОУСТ' in a distressed, carved wooden or thorny runic font, and the author name 'Оксана Абрамкина' in elegant white capital letters below.
