Oops, I Swapped with a Dragon Princess

Quinn transmigrates as a dragon sacrifice. A system glitch swaps him with Black Dragon Princess Eve. He binds the Soul King System. The Soul Tide comes in one year. To survive, he must sign 5 Soul Contracts. His first pact triggers 10000x Return: Low-Tier Fireball becomes Worldflame. In a dragon body, he acts “Hero vs. Dragon” to complete his quest.