A Mere Unicorn Cub

Rumor has it that the Three Realms Demon Locking Tower suppresses an extremely ferocious and terrifying ancient beast. Once it is born, it will destroy the world, bring disaster, and devastate all life in the three realms. The new Demon Lord sneered at this and smashed open the Demon Locking Tower, planning to confront the ancient beast for a while. The giant tower collapsed, and the demon king stepped into the formation with his sword. He saw a unicorn cub as big as a dumpling trembling all over, baring its teeth at him with tears on its face, and the ferocious beast roared: "Aww!" Demon Lord: "???" Intention: How can a mere cub destroy the world?