Smallville Season 10 Episode 5 (Smallville s10e05) with title “Isis” aired on Friday, October 22nd 2010 at 08:00 pm via CW Network.
Here is summary for Smallville Season 10 Episode 5 :

Lois decides to tell Clark she knows he’s the Blur, but she accidentally activates an ancient artifact that transforms her into the Goddess Isis, complete with superpowers of her own. Oliver Clark reluctantly decide to ask Tess for help with Lois. Meanwhile, after Cat Grant witnesses Lois as Isis using her superpowers, she decides Lois is the Blur and sets out to prove it.