You can watch this pivotal episode on Paramount+ and Apple TV . Bitter Reunions - Danny Phantom (Season 1, Episode 7)
In the seventh episode of Danny Phantom season one, titled " Bitter Reunions ," Danny meets Vlad Masters, a wealthy acquaintance of his parents who is revealed to be a powerful, experienced half-ghost with a vendetta against Jack Fenton. While attending a college reunion in Wisconsin, Danny confronts this new villain, who seeks revenge for a past lab accident and desires to take Maddie, forcing Danny to protect his family and his father. [S1E7] Bitter Reunions