Amulet of The Old Voice

This iridescent medallion shimmers oddly even in the dark. Its yellow eye glows with a golden aura, drawing your concentration into the murky depths of its cat-like iris. Anyone staring at the medallion intently begins to have a nagging sensation of unease. When attuned, The Old Voice sends images of the power that can be had by embracing the dark depths. The longer you court this voice, the more appealing it sounds. Your Spell Save DC and Spell Attack increase by 1. You also gain a swimming speed equal to your walking speed and can breath under water. 

Notes: Bonus: Spell Save DC, Bonus: Spell Attacks, Bonus: Speed (Swimming), Warlock (The Great Old One, The Hexblade, or The Fathomless) or a Sorcerer (Shadow, Aberrant Mind)