Prismancy

Light is almost everywhere. It fills otherwise empty space, and travels at imperceptibly high speeds. Some mages have compared and researched this invisible energy, finding it to be similar to the Weave itself. They began creating radiant spells of their own, free from divine intervention. During these same studies, techniques were discovered that were able to split radiant magic into many different types of energy. By using clear prisms made of highly magic-conductive material, this power can be used to convert and control even the most powerful radiant spells. Some of these self-proclaimed Prismancers have even unlocked a greater power, turning their crystal conduits a deep black to harness the power of the void...

Prismatic Conduit

When you become a Prismancer at 2nd level, you come into possession of a special spellcasting focus: a clear triangular prism, which splits light into each individual colour when it passes through. If you lose this prism you can replace it by spending the same time and cost that you would to replace your spellbook, at the end of which the prism magically reconstructs itself in front of you.

You learn the light cantrip if you do not already know it. Otherwise, you may choose to learn any other cantrip from the Wizard spell list.

When you cast light through this prism, you can instead choose to make a ranged spell attack against a creature you can see with a range of 30 ft. On a hit, you deal 1d6 radiant damage and the target is subjected to the regular effects of light as if they had failed the saving throw. This damage scales with your other cantrips, increasing to 2d6 at 5th level, 3d6 at 11th level, and 4d6 at 17th level.

Prismatic Conversion

At 2nd level, you can use your Prismatic Conduit to convert radiant energy into other forms of magic. Whenever you deal radiant damage, you can choose to convert that damage into any other damage type, other than necrotic, force, bludgeoning, piercing or slashing.

At 6th level, you can also choose necrotic damage as an option for your Prismatic Conversion.

If you use this abiility when dealing radiant damage to multiple creatures at the same time, you must choose a separate damage type for each creature. If all possible damage types have been exhausted, you may choose from the list as if starting from scratch.

You may use this ability a number of times equal to your Intelligence modifier, regaining all expended uses on a long rest.

Void Albedo

At 6th level, you can invoke an impossible darkness in your Prismatic Conduit, one that seems to devour the light around it. When an ally within 30 ft. of you takes radiant damage, you can use your reaction to turn your prism a pure black, absorbing that damage and having you take it in their stead.

You also gain resistance to radiant damage, and can now choose necrotic damage as an option for your Prismatic Conversion.

Photosynthetic

By 10th level, when not in dim light or darkness, you gain a +2 to your AC and can regain an expended use of your Prismatic Conversion once per minute.

Prismatic Fusion

As of 14th level, you can temporarily fuse with your Prismatic Conduit to conduct the weave yourself. Invoking your connection to the rainbow will grant you the power to share your light with the world and convert it freely, whereas calling upon your dark side will nullify it, warping the visible spectrum around you to obscure your position.

You can use an action to enter either Prismatic Form or Void Form. This form lasts for 1 minute. Once you have used this ability, it cannot be used again until you complete a long rest.

Prismatic Form: Any radiant damage that would be dealt to you is instead dealt to every creature in a 15 ft. radius around you, and you have unlimited uses of your Prismatic Conversion.

Void Form: You gain immunity to radiant damage. Any radiant damage dealt to a creature you can see is absorbed by you, and when in this form, you cannot be targeted by spells that require the caster to see their target.