Upon watching the 39th episode of a YouTubers DND series one chararcter had water elemental thrall, and this got me to thinking.

What about a multi element elemental, utilizing four elements but requiring a "main" element at the start.

For example, if you consider them as a dnd character, their race is elemental polymorphist or something. You have like... A stone golem, but their eyes are a mixture of the other three elements, water eyes, with fire sclera, air Iris, so they are burning blue eyes. And then as an ability can change between the other three elements as a free action, and this changes the eyes to be made of the other three elements. And their main body dictates the greatest number of spells of that element, and then like three minor spells of other elements. So like... Maybe there is a hell tree, and as an earthen body, can cause like... Earthquakes, but say they have an air body, at most they can cast stone fist. Something like that. The overall spells they can cast is the largest pool, but it's lowered by the body they have. As an earthen body, they have the full earth spell pool, but only another 9 spells total if they have three accessible per alternate element.

And as an elemental morphist, they can probably take on various creature forms. This could allow things like being able to be an air elemental wolf, utilizing the air elemental to be able to differentiate between smells better as an air elemental, using a wolven form to boost certain abilities. I suppose the story could somehow gain them more elements to increase their rather... Jack of all elements abilities. I suppose it would be like the protagonist from Forging his own way, but instead of being a chimera, he's an elemental.

Personalities could be their own concept for characters, as sometimes mixing and matching races and personas can alter abilities as choices vary widely between personalities. The plot is an important point but also is a separate point that could be made.