Do you longing Chloe (Allison Mack) on Smallville? Well, there is a good news for us. Allison will come back to Smallville Season 10. She will be appearing on episode 12th "Collateral" with Alaina Huffman (Black Canary). While Alaina only appears as cameo role in episode 11th "Icarus," but in episode 12th, there is an indication that she will come back not as a cameo.
Source : Kryptonsite.com