Pick one other race, from it you keep any skill proficiencies and, climbing, swimming, and flying speed it had; though you do not benefit from subraces or race variants.

Increase one ability score by 2, or two ability scores by 1. An ability score cannot be increased past 20 using this feature.

You can speak, read, and write Common, Deep Speech,  and one other language that you and your DM agree is appropriate.

Your creature type is aberration

Null commonly tend towards chaotic alignments.

Null can be conceived of any sentient race however, your size specifically is medium.

Your walking speed is 35 feet.

You can see in dim light within 120 feet of as though it were bright light, and in dark light as if it were dim light. You cannot discern colors in that darkness, only shades of gray.

You do not need to breathe, eat, drink, or sleep, and cannot be put to sleep by magical means. You will not age past what you were before becoming a null, and are immune to disease. To receive the benefits of a short or long rest, you do some light activity such as meditating.

You are immune to Psychic and resistant to Force damage. However, you are vulnerable to Radiant, and Necrotic damage. Although Null are thought to be undead, necrosis pushes them further along the path to madness.

You are privy to the ethereal noise generated by all sentient creatures. You have advantage on insight skill checks, and cannot be affected by short term madness.

Null make no sounds with their footfalls, do not leave prints, and cannot appear in mirrors. The silence of a null proves an excellent tool when attempting to move about unnoticed. You have advantage on stealth skill checks

Null are reviled by even the gods themselves. When entering a place of worship you burst into radiant flames, taking 1d4 radiant damage at the start of each of your turns.

When you are reduced to 0 hit points, you regain hit points equal to 1d8 + your character level. You then fall into madness for 1d12 rounds, whilst frenzied in this manner, you must use your action to make a melee attack against the nearest creature you can see, be they hostile or friendly. While in this state, you cannot concentrate on spells, or utilize spells which require a material component. If you are reduced to 0 hit points whilst in this state, you fall into a dormant state, and can only be awoken via spells such as revivify, or by being submerged in running freshwater for 1 week. If the madness ends naturally, you gain 1 point of exhaustion. Once you have used this feature, you cannot use it again until you finish a long rest; and the feature cannot be used if the damage which dropped you to 0 hit points was radiant. If you take radiant damage during your period of madness, you die.