Season 1: Episode 8 - "Jitters"

Official Wiki:

LuthorCorp is experimenting with meteor rocks, and overexposure to the rocks has caused employee Earl Jenkins (Tony Todd) to develop violent seizures. During a field trip to the local LuthorCorp plant, Clark and his classmates are taken hostage by Earl, who wants into "Level 3" (a secret testing facility at the plant) so he can find a cure for himself. Clark discovers "Level 3" just as Lex trades himself for the hostages. Clark reveals "Level 3" to Earl and Lex, but Earl's seizures put all three in danger. Clark manages to keep them all alive, and Lex makes a public statement that LuthorCorp will find a cure for Earl's condition.

Season 1: Episode 7 - "Craving"

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Jodi Melville (Amy Adams) is tired of being overweight, so she creates her own diet, which consists of meteor rock-infected vegetables. The new diet causes her to shed weight faster than she can handle, which forces her to suck human fat to satisfy her hunger. When Pete arrives to pick her up for the school dance, her hunger gets the better of her, and she tries to feast on Pete. Chloe and Clark discover the truth about Jodi's weight loss, and Clark rushes to her house to save Pete. Clark stops Jodi from killing Pete, and gets her the help she needs to maintain a healthy weight. Lex becomes interested in the effects of meteor rocks, and funds a study on the green meteor fragments.

Season 1: Episode 6 - "Hourglass"

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Clark meets an elderly-blind woman, named Cassandra Carver (Jackie Burroughs), who receives precognitive visions by touching someone. When she touches Clark both of them see Clark surrounded by the tombstones of everyone he loves. Lex visits Cassandra, after listening to Clark, and her vision of him entails blood raining from the sky. Harry Bollston (George Murdock), an elderly man at a nursing home, falls into a meteor rock filled pond, which reverses the aging process. Harry (Eric Christian Olsen) uses his new youth to get revenge on the children of the jury members that put him away for murder decades earlier, one of whom was Jonathan's father. Clark stops Harry before he can kill Martha, who happened to be home when Harry came looking for Jonathan.

Season 1: Episode 5 - "Cool"

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During a party at Crater Lake, Sean Kelvin (Michael Coristine) falls into the frozen lake and emerges with an insatiable hunger for heat, thanks to the meteor rocks on the lake bottom. In an effort to stay warm, Sean sucks the heat from anyone he can. Sean goes after Chloe, but Clark is there to stop him. Clark finds Sean, who is headed to Luthor Mansion, but is left frozen when Sean sucks the heat from his body. Clark's body reheats itself, and he arrives at the mansion just as Sean is about to attack Martha, who came with Jonathan to discuss their financial troubles with Lex. During the fight, Clark throws Sean into a lake, which immediately freezes with Sean inside.

Season 1: Episode 4 - "X-Ray"

Official Wiki:

Clark begins to develop X-ray vision when he is thrown through a window by Lex Luthor, who has just robbed the local bank. Clark witnesses a green glow around Lex's skeleton as Lex runs away. When it turns out someone was impersonating him, Lex is cleared of all charges. After gaining control over his X-ray vision, Clark discovers that Tina Greer (Lizzy Caplan) can morph into anyone she wants. He also learns that she robbed the bank when he X-rays her locker and sees the money from the bank. After a brief battle, Clark knocks Tina unconscious so the authorities can arrest her. Lex hires Roger Nixon (Tom O'Brien), an Inquisitor reporter, to find out how he survived driving his Porsche off a bridge.

Season 1: Episode 3 - "Hothead"

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A meteor rock infused sauna endows Coach Arnold (Dan Lauria) with pyrokinesis. After several football players are caught cheating, Chloe discovers that Coach Arnold assisted the players when they cheated. Coach Arnold asks Clark to join the football team, and Clark agrees against his father's wishes. Clark confronts Coach Arnold before his first game, after Arnold attempted to kill Chloe and another football player for exposing the truth about the cheating. The coach's fury gets the better of him as he engulfs himself in flames while battling Clark.

Season 1: Episode 2 - "Metamorphosis"

Official Wiki:

Greg Arkin (Chad Donella) gets into a car accident with his meteor rock-enhanced insects, which escape from their containers and begin stinging him. The resulting attack transforms him into a half man/half insect creature. Rapidly going through a metamorphosis, Greg kidnaps Lana so he can mate with her. After talking with Whitney, Clark realizes where Greg has taken Lana and leaves to rescue her. During the fight, Greg accidentally kills himself. Before Clark can return to Lana, Whitney arrives and receives credit for her rescue.