Your Intelligence Score increase by 1. 

You can speak, read, and write Common and Primordial. 

You are an aberration. 

You are Medium

Your walking speed is 25 ft. 

Being made of the very stars themselves, Aetherborn don't age like other creatures. Aetherborn are effectively immortal, and can live for thousands of centuries. 

You start with a Aetherian Containment Suit in addition to any equipment you gain from your class and background. A Aetherian Containment Suit is a biomechanical shell that reacts to your mental impulses. It allows you to travel outside of the Astral Sea to experience wild space, the material world, and other non-ether based planes.

For all intents and purposes, your suit is your physical form outside of the Astral Sea and acts as a representation of your physical health; when your suit takes a hit, it translates the damage into damage to your gaseous form, and you take a hit. If the suit is destroyed or heavily damaged (your hit points drop to 0), you risk dissipating (see the Aetherborn "Gaseous Form" trait).

Your containment suits provide an AC of 11 + your Dexterity bonus. If you are proficient with light armor, you may also add your proficiency bonus to your AC while wearing only your containment suit.

You can wear armor over your containment suit. However, you can use your containment suit to determine your AC if the armor you wear would leave you with a lower AC. A shield’s benefits apply as normal while you are wearing only your containment suit.

You may attune to magical items that require being worn, but the attunement process requires a long rest, as you take extensive care in integrating the magical item into your Aetherian Containment Suit. Once attuned and integrated in this way, the magical item cannot leave your possession without destroying your suit or unless powerful magics such as wish are cast to remove the item from your possession. It takes one long rest to swap a previously attuned magical item with a new item. 

As a non-carbon, gaseous lifeform, you gain a number of unique benefits:

• You are immune to disease and poison.
• You don’t need to eat, drink, or breathe.
• You don’t need to sleep and don’t suffer the effects of exhaustion due to lack of sleep.

With careful preparation, you can leave your Aetherian Containment Suit. If you willingly exit your containment suit and you are not in the Astral Sea, you take 1d4 + 1 necrotic damage at the start of each of your turns as your essence begins to dissipate. While outside of your suit, your only method of movement is a flying speed of 10 feet. You can enter and occupy the space of another creature, however, you cannot manipulate objects, wear equipment, or use weapons, nor can you make attacks. You have resistance to nonmagical damage, and you have advantage on Strength, Dexterity, and Constitution saving throws. You can pass through small holes, narrow openings, and even mere cracks, though you treat liquids as though they were solid surfaces. You can’t fall and remain hovering in the air even when stunned or incapacitated.

When you reach 3rd level, you can concentrate to maintain your gaseous form outside of your containment suit for up to 1 minute (as if concentrating on a spell) without taking damage. And at 5th level, you can concentrate to maintain your gaseous form for up to 1 hour. Once you use this feature to maintain your form, you can’t do so again until you complete a long rest.

If you are in the Astral Sea, you automatically maintain your gaseous form without taking damage.

Excessive damage to your suit causes your unconscious gaseous form to be violently vented into the surrounding atmosphere, dissipating rapidly. Once your suit is destroyed (your hit points fall to 0), a revivify spell can recombine your form and return you to your suit as long as it is cast within 1 minute of your suit’s destruction. However, other spells that would normally raise creatures from the dead such as raise dead or resurrection have a chance of failing depending on how long it has been since your suit was destroyed. For every day that your suit has been destroyed, there is a cumulative 10% chance that you cannot return from the dead. If 10 days pass and you have not been returned from the dead, only a wish spell or similar magic can bring you back.

When you take a long rest, you must spend at least six hours of it in an inactive, motionless state rather than sleeping. This gives your suit time to repair itself and for your gaseous form to recombine. In this state, you appear inert, but it doesn’t render you unconscious, and you can see and hear as normal.

You are proficient in one of the following skills: Athletics, Acrobatics, or Sleight of Hand. In addition, when you make ability checks using this skill, you can use your Intelligence modifier in place of the normal modifier.