Tori Spelling guest-stars in a pivotal, and stellar, episode of the superhero drama. She plays Linda Lake, a hateful gossip columnist whose ability to turn herself into water allows her to uncover secrets – like Clark (Tom Welling)’s true identity. Meanwhile, Lana (Kristin Kreuk) mulls marrying Lex (Michael Rosenbaum) or returning to Clark. Spelling’s turn is a campy kick, but it’s that bittersweet and brilliantly spun love triangle that keeps this show flying high. (CW, 8 p.m.)