Perun stands at the top of the Slavic pantheon as the god of sky, thunder, lightning, rain, law, and war. He is the protector of warriors and kings, the guarantor of oaths, the force that orders the world and drives away chaos. His eternal opponent is Veles, lord of the underworld — and their unending battle is not a conflict between good and evil but between sky and earth, upper world and lower, the forces that must eternally contend to keep the cosmos alive.
The central myth of Slavic religion — reconstructed by scholars Vyacheslav Ivanov and Vladimir Toporov from fragments preserved in folklore, place names, and folk belief — is the cosmic battle between Perun and Veles. Veles, dwelling in the roots of the World Tree, steals Perun's cattle (or wife, or children) and retreats to the underworld. Perun pursues him across the sky, hurling lightning bolts. Veles transforms — into a man, a horse, a serpent — trying to evade destruction. Each time Perun strikes him down, rain falls and the cycle of seasons turns.
This is not a story of ultimate victory. Veles is never permanently destroyed. The battle is cyclical — an eternal alternation that produces the weather, the agricultural year, and the movement of time itself. The thunderstorm is Perun driving Veles underground; the dry season is Veles's ascendancy; the next storm is Perun's return. The world is sustained by their conflict, not by either one's victory.
The Slavic cosmic myth is one of the most beautifully reconstructed in comparative mythology — a perfect Indo-European battle myth that illuminates not just Slavic religion but the common religious heritage of half of Eurasia.
— Marija Gimbutas, The SlavsPerun's sacred tree is the oak — the tallest tree in Slavic forests, most likely to be struck by lightning, and therefore most intimately connected to his power. His weapons are the lightning bolt and the stone or iron axe — both of which leave the same characteristic marks. Prehistoric stone axe-heads found by farmers were called "Perun's thunderbolts" and kept as protective talismans; they were believed to fall from the sky during storms.
His cult sites were mountaintops and high places — the peaks closest to the sky where his presence was most felt. His sacred animals were the eagle and the ox. In Kiev, the primary cult statue of Perun stood on a hill, his head silver and his moustache gold, a perpetual fire burning before him. When Prince Vladimir Christianised Rus in 988 CE, Perun's statue was thrown into the Dnieper River — an act of symbolic defeat that mirrors, with bitter irony, Veles's defeat in the myth.