Scare

S4 E10: A secret experiment that Lex is conducting at LuthorCorp goes terribly awry and causes the release of a dangerous toxin into the air. Smallville residents infected by the toxin--including Clark, Lana, Lex and Jason--imagine their greatest fears coming true and lapse into a coma. Desperate to find a cure, Clark gives some of his blood to Lex and is stunned at what his friend does with the antidote.