S08E11: The Warlock in the Gray Flannel Suit

Endora's causing trouble again! This time, instead of breaking up a marriage, she's breaking up Darrin's advertising company. She calls up Alonzo, a warlock who casts a spell on Larry, making him like all of his ideas on a carpet account instead of Darrin's. It gets to a point that Darrin quits McMann and Tate, but finds out that this is all Endora's fault. To get even with her, Samantha magically sets up an advertising campaign to handle the carpet account.