is his power that is already existing in first place. 2. Even though the boon granted was "one-arrow-one-shot and cities should be destroyed", Shiva has the ultimate power to rule them over. 3. Lord Shiva does not require a huge Chariot with Meru as bow, Vishnu as arrow etc. He could simply destroy/create anything even without moving his eyes. The "smile and burn" act of Shiva in Tamil is beautifully called as "sirinthuppurameritha peruman" ("சிரித்துப்புரமெரித்த பெருமான்")(God who laughed and burned the three purams) Mayasura Protected Lord Shiva immediately regretted his act, since he had forgotten to protect Maya, a great devotee of his. Realising this, Nandi raced ahead of the arrow and informed Maya of the impending doom. Instantly, Maya fled Tripura, leaving behind the great city he had constructed, which was immediately reduced to ashes, along with its inhabitants, the Asuras, by the great arrow of Shiva. This destruction of Tripura, led to the appellation Tripurantaka (त्रिपुरान्तक), for Shiva. References Matsya Purana Shiva Purana Locations in Hindu mythology