Tann was the individual who kidnapped children, including Kael, as free labor for his circus. Tann has a shardblade and when Kael’s father and other community members tried to rescue their children back, Tann slaughtered them all with his shardblade.
Tann is a cruel, unforgiving man who made his wealth off the back of slave labor. He puts up a front that he is rescuing these “orphaned” children, but in realty he is a slaver and a kidnapper.
Kael eventually escaped from Tann and his circus and at some point Elias, who survived Tann’s assault, found Tann - took his shardblade - and threw Tann in a cage.
Tann died after Elias threw Tann’s old shardblade at him during Elias’ fight with Kael.