Well, since it's your request that I'm trying to fulfill here I'll make him as you suggest. Expect stats for a non-Fomor Leviathan (with a lower power level and no spellcasting) later, since I don't want the idea to go to waste.
Greater Fomor Sorcerer (Snorkelling)
High Concept: Fomor Sorcerer
Other Aspects: Fishman, May Once Have Been Human, Behind The Scenes
Skills:
Superb: Conviction, Lore
Great: Contacts, Discipline, Intimidation
Good: Endurance, Presence, Resources
Fair: Athletics, Alertness, Weapons
Average: Fists, Survival, Might
Stunts:
Fomor Resources (Resources): May take a point of sponsor debt for +4 to a Resources roll that directly benefits Fomorkind.
The Boss (Contacts): May use Contacts to hire people.
Minions (Contacts): May use Contacts to declare the presence of lesser Fomors.
Powers:
Aquatic [-1]
Echoes Of The Beast [-1] Gives sonar, +1 to Alertness underwater, and the ability to talk to fish.
Fomor Magic [-0] Spellcasting requires nearby water rather than being prevented by it.
Evocation [-3]
Thaumaturgy [-3]
The Sight [-1]
Refinement [-4]
Inhuman Strength [-2]
Inhuman Speed [-2]
Inhuman Toughness [-2]
The Catch (unknown) [+0]
Magic:
Evocation (Earth, Spirit, Water): +1 water power, +2 water control
Thaumaturgy: +1 Fomor magic control, +2 Fomor magic complexity
Foci: Coral Staff (+1 offensive and defensive water control and power), Banner of Seaweed (+3 Fomor magic complexity)
Enchanted Items: 2 potion slots (strength 5)
Total Refresh Cost:
-22
Refresh Total:
-9