you gain dark vision and can see up to 60ft  in darkness as if its dimlight and dimlight up to 30ft as if its brightlight.

instead of food or water you now have to kill and via dark magics of a lost art you dont quite understand you can pull the soul from a body that was killed in the last minute to consume it to fuel your soul gem for up to 1 day per soul. only 7 souls can be consumed at one time and you will feel sustained and full after 1 soul is consumed after that you only become more bloated in feeling.

your strength decreases by 1 your constitution decreases by 1 and your intelligence increases by 2

you are a litch so depends do you want to be 30 years old and just became one somehow or 10k years old its up to you your literally immortal 

your size runs off whatever your original race was.

you are a still a skeleton your walking speed is 30ft 

you have the native tongue of common as well as one language you knew in life as well whatever language you learned while a litch during your studies

your bones are weak even if your magic is strong you have venerability to bludgeoning damage

no flesh no worries, you lack all that flesh which means no bleeding your immune to bleed damage as well as having resistance to slashing and piercing damage.

your body is melded to a suite of armor that keeps your body together and protects your bones you have a perm. AC of 18 as a base ac however due to this your body is sustainable to corrosion. you as well can not wear any other kind of armor on top of your body.

you no longer suffer the effects of ageing, food or water needs or the need to sleep however you do require downtime to rest your manna and recover your bodies magic stores so you must rest while awake for 8 hours a day as a long rest however you are alert during this time.

due to having your entire body made of magic if you enter a anti magic field you fall apart and lie unconscious till your body is gathered together outside of any field your trapped in your body must have your soul gem and if your left unconscious for more than days your gem has souls stored than you lose all your manna and die this period is minimum of at least 24 hours from entering the field.

your a walking immortal skeleton, the sight alone of that will scare most people you have proficiency in the intimidation skill when you reveal your true nature of being a litch to someone for the first time.