Your current form and power is no longer your maximum. Rather, it is your new minimum. At night, just after dusk and until dawn, you are as you are now. But the moment Dawn breaks, you begin to grow in power, magic, size and pride. As time progresses towards dawn, you will grow stronger and stronger, physically and magically, as well as more and more of a paragon of your race in appearance. You will begin to give off waves of light that are so hot that they can easily melt even the armour of a holy knight or gather this light into a miniature sun in your hand. When the sun hits its’ noon point, you will enter the state known as The One, a form so powerful that anything short of the Demon King himself is essentially powerless against your might, as well as having grown to gargantuan sizes in comparison to your original form. During the day, the burning light that emanates from your body will also suffuse your soul, affecting any who try to attack or devour it. This power will begin to leave you as the day turns from Noon towards Dusk, finally disappearing entirely as night falls and awaiting until the next day. You also gain the Divine Axe Rita if you wish it.
Project V17/Powers/Shardless/Magic and Mystic Powers/Sunshine (The Seven Deadly Sins)
From Worm CYOA Wiki
Eternal Sunshine
Your nature as a sun infuses your magical abilities gained from Sunshine, you are now always at your peak, perpetually at Noon, as long as you allow it, for you can dampen and raise your magical power as you please. Furthermore your flames and heat enter a new level, as the combined magical powers of a sun and the magical properties of sunshine enhance each other exponentially.