From time to time, one of the All can be divided from the One and All mind. This is a traumatic event, and it is rare that the severed member of the All survives, let alone becomes a solitary One. But from time to time, it can occur. Seeking succor from the desperate silence in its mind, the One Beneath The Waves has sunken himself beneath the oceans of Shamash II, and there it lies, seeking fruitlessly to soothe its injuries.
Magic should have side effects, both expected and unexpected - fortuitous and deplorable. Expected side effects add anticipation, while unexpected ones increase the drama of the scene. The result can be comedic or dire, it dpends on which circumstances work best for your game.