School of Theurgy

All wizards pour over tomes and manuscripts, trying to understand the machinations of the universe. While clerics receive divine magic by prayer and worship, theurgists bend divine magic to their whims.

Consider the relationship between you and the divine. Are you an acolyte of the gods, using magic to understand their true nature? Are you devoted to a god of knowledge, arcana and understanding, that encourages its followers to pursue deeper understanding of the world and the powers that be? Are you dismissive of the gods, denouncing their worship as a waste of time, while feeding off the same source of power that many a cleric or a paladin do, the positive and negative planes? 

Note: This is a revamp of the Theurgy wizard subclass made by  u/Jaridase. I had changed a few features around, but apart from it, the final product is very similar to his brew. Check his work out!

Religious Savant

At 2nd level, you have the ability to learn spells that are on the cleric spell list. Whenever you learn spells from leveling as a wizard, you can replace one of the two spells you learn with one from the cleric spell list. You can also select cleric cantrips instead of wizard cantrips. Any cleric cantrip picked is considered a wizard cantrip for you. Additionally, you can add cleric spells to your spellbook if you find them on scrolls or religious tomes. You treat them as wizard spells when you cast them, but they are not eligible to be used as spells for your Signature Spells feature at 18th level. Other wizards will not be able to copy these spells into their spellbooks unless they also have this feature. Furthermore, the time and gold it takes to copy a spell that is on the cleric spell list into your spellbook is halved.
Lastly, you gain proficiency in the Religion skill. If you are already proficient in this skill, you gain expertise in it.

Channel Arcana

Once you've reached 6th level, you've learned how to channel magic with the perfection and purity that the gods do. You can Channel Arcana to empower yourself.
You gain one of the options presented at the end of this feature description, Negative Empowerment or Positive Empowerment, as your effect, depending on your choice for your Tracing the Source feature.

Negative Empowerment

When you roll necrotic damage, or give a creature temporary hit points, you can use your Channel Arcana to reroll any dice that land on 1 or 2. 

Positive Empowerment

When you roll radiant damage, or roll to heal a living
creature, you can use your Channel Arcana to reroll any dice that land on 1 or 2.

Henosis

By 14th level, you have learned enough about the workings of divinity to create a permanent change in yourself. You become a Celestial, meaning your creature type permanently changes to Celestial.
As a Celestial you cease to age, and are immune to magical aging. You no longer need to eat or drink for sustenance or to recover from exhaustion, although you still need to sleep and rest, and may eat or drink for your own leisure. You no longer need to breath. Resurrecting you no longer requires material components, and ignores age and time restrictions. You have immunity to
disease, poison, and the poisoned condition.

Tracing the Source

Also at 2nd level, you must choose which source you are using to fuel the divine magic that you'll be using. Choose either the Plane of Negative Energy or the Plane of Positive Energy. This choice cannot be changed.
If you chose the plane of Negative Energy, you learn the cantrips chill touch and spare the dying as wizard cantrips. They do not count against your number of cantrips known.
If you chose the plane of Positive Energy, you learn the cantrips sacred flame and spare the dying as wizard cantrips. They do not count against your number of cantrips known.

Negative Energy Plane

Your magic stems from the plane of negative energy.

Positive Energy Plane

Your magic stems from the plane of positive energy.

Theurgist's Recovery

Starting at 10th level, when you use your Arcane Recovery feature, you gain specific benefits depending on your choice for your Tracing the Source feature. If you chose the Plane of Negative Energy, you gain temporary hit points equal to double your wizard level. These temporary hit points last up to 4 hours. Additionally, while you have these temporary hit points you ignore the effects of exhaustion and have resistance to necrotic damage.
If you chose the Plane of Positive Energy, you regain hit points equal to your wizard level. Additionally, you can recover from one level of exhaustion immediately.