Trigger Truth is Trigger's final form gained by combining the power of both his own light and Trigger Dark's darkness in preparation for his final battle against Megalothor. Due to possessing both Trigger's light and darkness, Trigger Truth is dubbed the "true Trigger". This form of Trigger can naturally harness the energy of the Eternity Core without exhaustion, a feat that proved vital during the final battle against Megalothor.

After some reconciliation, the team had come to the conclusion that a power equal to Megalothor's was needed in order to blow it away. Kengo and Ignis were reminded that Trigger was once a giant of darkness, and that Trigger Dark was once able to use Glitter Trigger Eternity's power, which gave them the idea of restoring Trigger to his "true" self by combining light and darkness. Betting everything on this last gamble, Ignis gave Trigger Dark's power to Kengo's Multi Type key, changing it into the Trigger Truth key. With this new item, Kengo transformed into Trigger Truth, who wielded the powers of both light and darkness within him, to fight Megalothor again, with Carmeara inside the monster cursing at him for his new form.