Matsya Purana — Uma’s Austerities and the Slaying of the Deceiver Asura ĀḌi
इत्युक्तो ऽमरतां मेने दैत्यसूनुर् महाबलः तस्मिन्काले तु संस्मृत्य तद्वधोपायमात्मनः //
ityukto 'maratāṃ mene daityasūnur mahābalaḥ tasminkāle tu saṃsmṛtya tadvadhopāyamātmanaḥ //
Thus addressed, the mighty son of the Daitya deemed himself to have attained immortality; but at that very time, recalling for himself the stratagem for his slaying, he reflected upon the means by which he could be killed.
This verse does not address pralaya directly; it highlights a common Purāṇic theme: apparent invulnerability or “immortality” is still conditioned and can be undone by a remembered or destined means of death.
Ethically, it warns against arrogance born of power or boons: rulers and householders should act with humility and foresight, recognizing that security based on pride is fragile and that consequences (karma and polity) have “means” that catch up.
No Vāstu, temple-building, or ritual procedure is specified in this verse; its focus is narrative psychology—confidence in deathlessness and the recollection of a ‘vadhopāya’ (method of slaying).