E.F.T

Three Legionnaires from the future will appear - and if you're guessing it's the same roster that appeared in their first appearance way back when, you guessed correctly... the three Legionnaires will be Garth, Imra, and Rokk, who have powers of electricity, telepathy, and magnetism, respectively.

UPDATED 10/2/08: The threat of Brainiac - who has taken over Chloe's body - brings three super-heroes from the future back to the past. Eventually they work together to try and separate Chloe from her Brainiac side.
- Erica Durance, Aaron Ashmore, Cassidy Freeman, and Justin Hartley do not appear in this episode.

That Legion villian appearing in the episode was seen in the CW's promo for January 2009 - the character is the Persuader.

Source: Kryptonsite