Spell Save DC is 8 + your proficiency bonus + your dexterity modifier 

Point Energy

The elements are used with a point system. Each tier has a different amount of points, the higher tier you are, the higher amount of points you have. The amount also depends if you’re a Demigod or Natural. Points are replenished every long rest.

Physical Features

For Demigods, they summon their water and their eyes will glow an ocean blue. Their hands will crack with deep blue energy that flares up into light blue whenever they use their abilities. Their hair also appears as if the user is underwater. 

For Naturnals, when they summon their elements, their hands crack with their element’s color. However their hair and eyes do not change, many Naturnals use this to help with their stealth by wearing gloves. However most Naturnals need stances and forms to do their elements, unlike Demigods who simply summon it. Demigods can also breathe underwater while Naturnals cannot. Users also have a base swimming speed of 30 ft.

Fuel and Base Focus

Every element has something called Base Focus. This focus is what the user bases their magic off. In the case of water, the user must focus on going with the flow.

Strengths And Weaknesses

There are 4 stats of the elements:

Strength - How strong it is

Movement - How well you can move

Control - How easy it is to use

Speed - How fast is it

Each element has 2 stats they excel at and 2 stats they lack. Water excels at Movement and Control, but lacks Strength and Speed

Running Out of Points

When you run out of points you can go negative. However you can only go up to -10. Each time you use your negative points you gain one level of exhaustion that doesn’t go away until you take a long rest. If you reach -11 or higher then you die from elemental exhaustion. For water you notice that going negative makes you dehydrated and if you go over, then your body dries out and withers.