Matsya Purana — The Battle at Tripura: Shiva’s Strategy
अम्बुदैराकुलमिव हंसाकुलमिवाम्बरम् दानवाकुलमत्यर्थं तत्पुरं सकलं बभौ //
ambudairākulamiva haṃsākulamivāmbaram dānavākulamatyarthaṃ tatpuraṃ sakalaṃ babhau //
That entire city appeared utterly crowded with Dānavas—like the sky thronged with rain-clouds, like the heavens filled with flocks of swans.
It does not describe Pralaya directly; it uses cosmic imagery (cloud-filled sky) as a simile to convey overwhelming numbers, not dissolution.
Implicitly, it frames a crisis of public order: a city swarmed by hostile forces. In Purāṇic ethics, such scenes underscore a king’s duty to protect citizens and restore dharma through defense and governance.
No Vāstu or ritual rule is stated; the verse is a poetic city-description. Its takeaway for cultural history is how Purāṇas depict urban spaces as vulnerable to invasion and mass movement.