The story begins shortly after Thorax helps the Badlands Swarm reform. MLP FIM is mostly canon, but a bit more combative.

Thorax now leads the Reformed Changelings. However, this is a new experience for him, and he must rely on old and new friends alike. While the Changelings pick themselves back up shadows have begun growing to the north west, and the horns of war sound in the north east.

Can Thorax and his brother keep the Swarm together or will it fall back into the darkness it fought so hard to leave?