In Slavic Mythology, Perun is the head deity in the pantheon, deity of war lightning and thunder, purifier and overseer of law, greatly similar to the Norse deity Thor; he usurped his father Svarog's status as the head deity. He's associated with the eagle and the oak, his favorite weapons being the Axe or Hammer along with arrows and lightning bolts. His lighting bolts supposedly pass through the earth to a certain depth and slowly resurface. The word Thursday (Thor's Day) in the Western Slavic language was Peründan, referring to Perun.
His enemy is Veles, a complete counterpart of Perun, their battles being incredibly significant through Slavic mythology, and this cosmic battle was seen to be similar to God and the Devil following the Christianization of the Slavs.