Ahh, but it's only attack in the original text is a lightning bolt. Though you could convince me to give it a slam attack rather than a melee shock.I'm okay with having a strong wisp. It is serpentine in shape... perhaps it strikes with its body?
I knew there must be an example somewhere. So let's have the descriptor do something.There is! Prismatic spray, for example, can do energy damage, but just has the light descriptor.
These creatures have shown themselves to be adept at mimicking the shape of a ship or lighthouse. The will o’ sea, unlike the will o’ wisp, is unable to turn invisible, but can dampen its glow somewhat.
If it appears as if the inhabitants of a vessel are going to escape with their lives, the will o’ sea will take a more direct approach, using its vast energies to attack with a powerful lighting bolt. The evil entity can release such a stroke once every three rounds. The bolt does 10-60 (10d6) points of damage and has a 50% chance of setting wooden vessels alight if a saving throw vs. lightning fails.