Matsya Purana — Tārakāsura’s Austerity and Boon; Mobilization for War; Bṛhaspati’s Fourfold P...
भुजगेन्द्रसमारूढो जलेशो भगवान्स्वयम् नरयुक्तरथे देवो राक्षसेशो वियच्चरः //
bhujagendrasamārūḍho jaleśo bhagavānsvayam narayuktarathe devo rākṣaseśo viyaccaraḥ //
The Lord of the waters—God Himself—should be depicted mounted upon the king of serpents. The deity who rides a chariot drawn by men is the lord of the Rākṣasas, who moves through the sky.
It does not describe Pralaya directly; it functions as an iconographic identifier, specifying how certain deities should be depicted (their vahana and mode of movement).
Indirectly, it guides righteous patronage: kings and householders commissioning temples or images should follow śāstric markers so worship is properly directed to the intended deity.
It gives pratima-lakṣaṇa (image-identification) cues—Varuṇa associated with the serpent-mount, and the rākṣasa-lord characterized by a man-drawn chariot—useful for temple sculpture programs and ritual visualization (dhyāna).