Smallville: Season 7, Episode 7

7 - 7: Wrath

Kryptonite and high voltage mix during a lightning storm, causing Lana to absorb Clarks powers. Using her newfound super powers, she breaks into Lex's safe and steals incriminating evidence which she then delivers to Lois and Grant, demanding they run a story exposing Lex's secrets. After Grant refuses to use stolen material, Lana decides to take care of Lex herself. Clark tries to stop Lana from killing Lex and a super battle ensues between the two.