After his victory over the changeling queen Lilith from the Red Hive, Irradiance has settled into his new role as Princess Twilight Sparkle's student. With newfound fame and recognition, life seems brighter than ever for Irradiance and his friends. However, an unsettling disturbance brews in the depths of the Everfree Forest. An ancient Element Tree, once thought dormant, has reawakened, siphoning Irradiance’s magical power and threatening to undo his hard-earned achievements.

As Irradiance and his friends uncover a long-lost legend regarding a long-forgotten princess, will the stallion succumb to the loss of his power, or will he defeat this foe just like the last?