Notes from the Palm: It struck me that wandering around a desert in full plate made none of the sense, so heres a paladin oath that takes that into account!
Addendum: Any similarities to warriors of any other sun-worshiping tradition are purely coincidental. Praise the Sun.
Oath of the Sun
In the wastes, the sun is a double-edged sword: though it brings light, warmth, and nourishment to the little greenery there is in the desert, it also burns, blinds, and can destroy those who do not respect it. Paladins who take the Oath of the Sun understand the sun's dual nature, and strive to both bring its light to the darkest reaches of the world and to protect those who fall prey to the sun's rays out of happenstance or misfortune.
Unlike other paladins, most brothers who take the Oath of the Sun belong to a clergy of a sun god of some sort, be it Amaterasu, Apollo, Ra, or any other. They most often serve as templars, protecting their temples from raiders, bandits, and more supernatural threats. They are uniformly good, though their adherence to laws other than that of their faith is sometimes shaky.
Tenets of the Sun
The Oath of the Solar Brotherhood is always taken in public at the height of noon, among the congregation of the paladin's church.
The Sun Rises. The sun rises over the horizon each day, without fail, spreading light over the whole of the world. So should you never fail in your task to spread your faith and knowledge every day.
The Sun Blazes. Under the noonday sun, only the pure may survive for long. Those that fear the sun must see its light, so as to burn away their impurity.
The Sun Sets. The sun must rest each night, and give the world a chance to sleep. So too should you give rest to your fury and righteousness in the service of mercy, though only to those who deserve it.
Oath of the Sun Spells
3rd absorb elements, burning hands
5th darkvision, scorching ray
9th daylight, spirit guardians
13th fire shield, wall of fire
17th hallow, immolation
When you take this oath at 3rd level, you gain the following two Channel Divinity options.
Glorious Radiance. As an action, you can begin radiating bright sunlight. While this effect is active, you shed bright light out to a radius of 30 feet. Additionally, you gain a number of temporary hit points equal to your paladin level + your Charisma modifier. If a creature hits you with a melee attack while you have these hit points, you can use your reaction to deal 5 points of radiant damage to it. This effect lasts for 1 hour, until the hit points are expended, or until you dismiss it. When you reach 9th level, the effect deals 10 points of radiant damage, and at 17th level, it deals 15 points of radiant damage.
Solar Flare. As an action, you can emit a blinding flash of light. When you do so, all creatures you choose within 20 feet of you must make a Dexterity saving throw or be blinded for 1 minute. An affected creature may make a Constitution saving throw at the end of each of its turns to end the effect.Sun's Warmth
At 7th level, you and all friendly creatures within 10 feet of you have resistance to fire and cold damage, and can tolerate temperatures as low as -50 degrees Fahrenheit and as high as 300 degrees Fahrenheit. Additionally, when you deal fire damage, you can choose to deal radiant damage instead, or vice versa.
At 18th level, the range of this aura increases to 30 feet.
At 15th level, the damage die for your Improved Divine Smite becomes a d10.
At 20th level, as an action on your turn, you can fill yourself with the sun's brilliant wrath. You may cast the spell sunbeam without using a spell slot. Additionally, at the start of each of your turns during this spell's duration, you regain hit points equal to your Charisma modifier if you have no more than half your hit points left. Once you use this ability, you must take a long rest before you can do so again.
6/17/16: Glorious Radiance: changed from an AC ability to a Temp HP ability.
6/30/16: Glorious Radiance: Duration no longer scales and extra damage requires a reaction