Stormbringer

Weapon

Very Rare

weapon of the deep: +2 to weapon and damage rolls and you do not suffer disadvantage from attack while under water

ocean's shock: the weapon holds 8 charges when you hit a creature with this weapon you can expend up to 3 charges to deal an additional 2d6 lightning damage per charge the weapon regains all charges after a long rest

I hear thunder: after a successful strike you can expend 1 charge to give the target lightning vulnerability until the end of your next turn