WARNING: The following contains spoilers for Season 2 of The Idhun Chronicles, available on Netflix.
Season 1 of The Idhun Chronicles didn't paint an optimistic picture for the magical heroes trying to free Idhun from the Necromancer Ashran. He had his general, Kirtash, wreaking havoc and killing Idhun's refugees on Earth, all to ensure there could be no mystical uprising against his kingdom following his coup. There were some rebels, with Shail and Alsan trying to train Jack and Victoria to fight back, but ultimately, that mission took a massive couple of blows.
Elrion, Kirtash's lackey, turned Alsan into a werewolf while Shail got killed outside Kirtash's castle. However, as the second season winds down, the rebels get a much-needed boost. It turns out that Shail's alive and well, building a network to continue the Resistance.
In Season 1, Shail disintegrated after he tried to save Vic from being lured to the dark side by Kirtash. However, Kirtash didn't kill him. He saved Shail by blasting him with teleportation energy because Elrion's blast of dark energy would have turned the mage to ash. The revelation occurs two years later this season when Ashran senses Kirtash's deceit, all stemming from Kirtash being in love with Vic. Ashran needs her magic to power the Drackwen tower up but Kirtash wants to protect her, so he brainwashes Kirtash after torturing him. It's all part of a reconditioning process to get his warlord back, which causes Kirtash to bring Vic to him so Ashran can start sucking in Idhun's latent magic once more.
However, as the tower activates, a masked mage notices it, rounding up wizards and witches to attack. Using flying beasts they try to raze the tower but when this particular soldier comes, seeing him awakens something in Kirtash. He was already feeling the loving connection to Vic rising up again and this person more or less reminds him what Ashran did.
As a result, Kirtash lowers the shields for the mage to enter. He and the masked warrior partner up, free Vic and make a break for it. It's then the mage unmasks, revealing he's Shail. When Ashran confronts the trio, Kirtash opens a portal and sends Shail and his student back through the Soul to Limbhad.
When Shail gets home with Vic, Jack and Alsan are ecstatic as they've missed him dearly. He admits he didn't know much of Kirtash's plans to turn on Ashran, but when he ended up in Idhun, he knew there was a bigger endgame happening. Kirtash wanted him to go back to strengthen the Resistance, all so when the day came that he needed them to attack the tower, they'd come. With that part of the plan complete, Shail now wants his allies in Limbhad to come over to end the war as he feels the time's right to strike back.
Both seasons of The Idhun Chronicles are currently available to stream on Netflix.