1 Episode 1 spellbound

In the late 12th century, Merlin catches his apprentice Hisirdoux "Douxie" Casperan in the act of using magic to finish his chores. Douxie wants to be a real wizard like Merlin, with a staff and everything, but Merlin tells him it takes time to master the magic needed to have one. Picking up where 3Below left off in the present, Douxie and Merlin's familiar, a talking black cat named Archie, catch a monster until Merlin summons them and instructs them to bring Tobias Dumzalski, Steve Palchuk and AAARRRGGHH the troll to their secret lair in a bookshop. The quintet are attacked by more monsters and a strange man in green medieval armor before retreating on an airship that Merlin conjures up. The teens reunite with Claire Nuñez and Blinky in Camelot Castle, --now a flying air fortress--,where they learn that, (during the events of 3Below season 2), Jim Lake Jr. the Trollhunter was attacked and encased in green crystal by the 'Green Knight' who Merlin learned is connected to his fallen apprentice and archenemy, Morgana Le Fay, and an Onyx Shard is slowly killing the poor hero. Just then, the Arcane Order - the evil organization the Knight's a part of- attacks, killing Sir Galahad and forcing Merlin to open a rift in time. However, during the attack, Claire, Steve, Douxie and Jim all fall into the past and awaken in Camelot's forest, where they are confronted by Sir Lancelot and his men.