Here is my spoiler-filled breakdown of why Season 3 is the turning point of the entire series.
Astrid contracts the Scourge of Odin, a fatal illness. The team races against time to find the rare Buffalord dragon, testing the deep emotional bonds between the core characters. "To Berk and Beyond" Dragons Race To The Edge - Season 3
Dagur the Deranged returns, appearing to have a change of heart and seeking a reunion with his sister, Heather . Here is my spoiler-filled breakdown of why Season
We also see the return of the (flightless, blindingly fast dragons) and the Catastrophic Quaken , which becomes a recurring ally. Dragons Race To The Edge - Season 3
Season 3 moves the side characters out of Hiccup’s shadow.