Arcane Torpedo Bombers

You conjure a wing of miniature spectral torpedo planes which target a 20ft. sphere underwater. All creatures within this area must make a Dexterity saving throw or take 4d8 force damage and be revealed to the caster, at the beginning of the affected creatures' next turn they take 1d8 additional force damage. on a success the creatures are not revealed and take half damage on the initial strike and no damage at the beginning of their next turn. If the target is Gargantuan and a construct increase all damage dealt by 1d8.