Nammuabzu

Something gargantuan and dangerous lurks in the deeps of the oceans of Oerth. Its voice, or more accurately its chaotic and turbulent thoughts translated into a comprehensible form, can reach across countless leagues to those whom it has touched. These telekinetic pulses weigh on the receiver's mind like the slow but inexorable ebb and flow of a tide pushing against someone half-buried in sand; a powerful but shallow touch from something much deeper and more inevitable.
This creature is ancient beyond reckoning, a primordial power from another time and place. Such a creature has no true name, but there are those throughout the ages who have worshipped it as Nammuabzu. In some old tongues, now largely lost to all but the most esoteric scholars, the name roughly means "First of the Sea" or "Birthed of the Sea".