You will Watch Phineas and Ferb Season 4 Episode 17 online for free episodes with HQ / high quality. Stream cartoons Phineas and Ferb 417 Terrifying Tri-State Trilogy of Terror. This new episode of “Phineas and Ferb” features three separate tales. Tale One follows Candace as she accidentally conjures up a spell that turns her Ducky Momo plushie into a living, breathing doll that is set on stalking her. In Tale Two, Doofenshmirtz encounters a mythological, giant floating baby head that grants cursed wishes; and Tale Three pits Phineas, Ferb and their friends against a horde of mischievous, evil platypuses set on destroying the town.