Arcane Tradition
Notes from the Nails: I went on a trip to Malta recently, and the ancient ruins there inspired me to explore the early history of wizardry with this subclass.
School of Prehistoric Wizardry
Long ago, wizardry was not an old and venerable profession: it was a new discovery not yet fully understood or codified into formal schools. You are one of the first ever wizards, bending the universe to your will before even the invention of writing. Perhaps you witnessed a spellcasting monster or one of the first humanoid sorcerers and wanted to emulate their power, or maybe the idea came to you in a dream. Whatever your inspiration, you are determined to unravel the secrets of magic, despite the limited technology available to you.
Groundbreaker
As one of the first of your kind, you do not have the luxury of following the example of previous wizards. Instead, you must devise all of your spells for yourself, from first principles. Starting at 2nd level, you can add 3 new spells to your spellbook every time you gain a level in this class, rather than 2. However, you cannot copy spells into your spellbook from outside sources.
Sticks and Stones
Also at 2nd level, the harsh conditions of the stone age mean that even a wizard like you needs some competence with conventional weapons. You gain proficiency in simple weapons and light armor.
Solar Alignment
By 6th level, your studies of the heavens have given you unparalleled insights into the movements of the stars. As long as you can see the sky, you always know the exact time and date, as well as which way is north.
Furthermore, by synchronizing your magic with the rhythms of nature, you can extract more power from certain spells. Whenever you cast a spell that would deal cold, fire, or lightning damage, you can add your Intelligence modifier to the damage dealt.
Trepanning
At 10th level, you are able to recognize when your allies are under the influence of evil spirits, and quickly save them. You can use an action to perform a Wisdom (Medicine) check in relation to a creature within 5 feet of you that is charmed, frightened, or possessed (such as by a ghost). On a roll of 10 or more, the creature is no longer affected by any of those conditions but, on a roll of 15 or less, the target takes 1d4 bludgeoning damage.
Arcana of Survival
When you reach 14th level, you learn to siphon off some of the power of your spells to heal yourself when you are wounded. Whenever you use an action to cast a spell of 1st level or higher, you can use a bonus action to recover lost hit points equal to the spell’s level.
Sidebar: Spellbooks Before the Invention of Writing
As a prehistoric wizard, you are unable to read and write. However, you still require a way to record your spells so that you can memorize the ones you need each day. Therefore, you have devised some unique system for representing your spells, such as a collection of figurines, a carved stone slab, elaborate tattoos, a painted cave wall, or a necklace of cunningly-ordered beads. Whatever form your spell-record takes, it functions exactly as per the standard spellbook of a modern wizard (except for the restrictions noted in the Groundbreaker feature).