Varuna

Though he only has about a dozen hymns addressed to him in the Rig Veda, Varuna seems to be one of the most important of the Vedic gods. In pre-Vedic times, he was the supreme lord of the cosmos, the keeper of divine order, the bringer of rain, the enforcer of contracts. He is called omnipotent and omniscient; he is responsible for the sun to move in the sky, for day and night to stay separate, and for the earth to keep its form; he watches the flight of every bird, is present at every gathering, and knows every thought.

His name means "he who covers", and this probably refers to the sky. Varuna is the keeper of the cosmic order, a force called rta. It is rta which keeps everything working as it should, and Varuna's role as the one who governs rta makes him very important indeed. He is very closely linked to the god Mitra. Varuna is one of the Adityas and considered to be an asura, when those beings were still god-like and had not yet degenerated into demons.
Varuna is the keeper of the celestial waters, those which flow from the openings in the sky in the form of rain. He was worshiped with veneration and a healthy amount of fear, for as an asura Varuna did have his sinister aspects and was known to punish mortals who did not keep their word. He was the cosmic hangman and his usual method of punishment was to capture the offender with his noose. He was also a lord of the dead, a position he shared with Yama, and could confer immortality if he so chose.

Varuna faded away with the ascendancy of Shiva and Vishnu. His lofty position may have lived on, however, for he may be the same as the Zoroastrian supreme god Ahura Mazda.
From here.

Varuna's supernatural power is called Maya - "illusion" and "magic".

Art by Deva.