Spoilers for 6.09 "Subterranean"

[Vilandra]

08/18 - There are some immigrants being exploited at a farm that neighbors the Kent Farm. A teenage boy escapes and is rescued by Clark. Clark investigates the farm and finds many of the immigrants are being used there as slaves. Lionel and a doctor have a chat about a mysterious patient's condition. Source: secretagentman via KryptonSite
07/21 - Title is from KryptonSite.

Source: SpoilerFix (http://spoilerfix.com/smallville.php)

[Vilandra]

11/01 - In Episode 9, a new Phantom Zoner is going to surface and draw Clark to Seattle for a showdown. We will learn that there is a secret LuthorCorp lab where meteor-freak patients from Belle Reve are sent — instead of being released, as they think they are — for gruesome testing. And someone will escape and come looking for Lex. Source: Ask Ausiello @ TV Guide

Source: SpoilerFix.com (http://www.spoilerfix.com/smallville.php)

[Vilandra]

11/20 - Clark is shocked to discover his neighbor Jed McNally (guest star John Novak) is holding migrant laborers captive and forcing them to work on his farm. Feeling guilty since he sees himself as the ultimate illegal immigrant, Clark seeks help from Martha to allow a young boy (guest star Tyler Posey) and his mother (Maria Dimou) to stay in the country. Kristin Kreuk, Michael Rosenbaum, Erica Durance, Allison Mack and John Glover also star. Source: The CW

11/20 - An illegal immigrant from the nearby McNally farm seeks help from Clark, who soon discovers a sinister secret buried in the farm's cornfield, which had been bombarded during the last meteor shower. Source: TV Guide Online

Source: SpoilerFix.com (http://www.spoilerfix.com/smallville.php)