Summoning A Forbidden Star

In the architecturally resplendent city of Sargona, people lived in utter harmony, observing the changing cosmos, and celebrating celestial phenomena. Magic and science coexists here, honed and practiced by a specialized sect known as 'Astro-Sages'. They were initially astronomers but have grown to understand and manipulate the cosmos' secrets. They were governed by the king, whose bloodline preserved an ancient star relic, protecting the city from metaphysical disturbances.
One Astro-Sage, Savareus, infamous for his insatiable curiosity, ventured towards the forbidden. Blinded by ambition, he decided to summon the 'Nebula Dragon', a ancient cosmic entity. Chronicled within the library's darkest corners, the 'Nebula Dragon' was a force of destruction, capable of obliterating cities with its starry breath. Savareus, however, craved its power, lured by the promise of immortality.
Meanwhile, Lyra - the king's daughter and the city's staunch protector, foresaw Savareus's dangerous aspirations in her stargazing sessions. An accomplished Astro-Sage, Lyra's skills surpassed many, her intuition defined by the star relic. Using her wisdom, she decided to intervene with the unwitting help of her childhood friend, Orion.
The night Savareus decided to summon the Nebula Dragon, Orion, upon Lyra's insistence, stole into Savareus's laboratory. Orion, a thief blessed by the night, traversed the labyrinthine Academy of Astro-Sages with dexterity. He reached Savareus's laboratory, just as the vortex for the dragon was conjured. Orion, equipped with a mirror polished to reflect deeds not stars, held up the mirror to the vortex. As the Nebula Dragon began materializing, its ethereal form got trapped within the reflecting surface of the mirror.
Savareus shocked, tried to counter Orion, but was too late. His grand plan disrupted; he turned into ash, succumbing to his own summoned entity's raw energy. Orion, unscathed due to the protective charm given by Lyra, returned the trapped 'Nebula Dragon' to her. Lyra, with her unshaken resolve, using the star relic, guided the entity back into the cosmos, averting the catastrophe.
The city of Sargona breathed a sigh of relief, unaware of the disaster that almost unfolded. The king, recognizing Orion's bravery, offered him a place in the palace. Lyra, relieved and proud, thanked Orion, seeking his service to the city henceforth. Orion agreed, citing it was high time he took responsibility for his city.
Sargona, under Orion and Lyra's new joined watch, prospered. The citizens' worldview shifted regarding the cosmos - fear and fascination replacing their zealous adoration. The celestial city continued to thrive under the starry sky, aware of its cosmic dangers and heroes ready to defend it.
Thus unfolded the story of a city saved by a brave thief and an Astro-Sage princess from a forbidden star's fury. A story of friendship, courage, and the necessary balance between curiosity and wisdom - a tale called 'Summoning a Forbidden Star'.