You're an Elemental. 

Your size is either Small or Medium. Most Frostlings are usually size Medium. 

You gain Darkvision of 30 ft. 

You have a Walk Speed of 25 ft and a Fly Speed of 15 ft. 

You have a pool of innate mana that your kind has to cast ice magics. Your mana pool can be used to cast the spells or cantrips in the Frostling Spell table. As long as you have mana in your mana pool, you can cast any of these cantrips. Spells you cast this way cost 1 mana per spell level of the spell cast. The amount of mana you have in your mana pool maximum starts at 1 and increases at certain character levels. Your mana pool maximum increases to the amount at the following character levels: Level 5; 3 mana, Level 9; 5, Level 13; 7, Level 17; 10 mana, Level 18; 13 mana, Level 19; 16, Level 20; 20 mana. If you have a Spellcasting or Pact Magic feature, you can use your mana pool to cast your non-9th level prepared spells and can use your spell slots to cast spells from the Frostling Spell table. You can also use the cantrips in the Frostling Spell if you have the Spellcasting or Pact Magic feature regardless of having mana in your mana pool. You recover 1d4+your Proficiency Bonus mana every time you take a Short Rest and you recover all of it at the end of a Long Rest. You use either your INT, WIS, or CHA stat, whichever is the highest, for your spellcasting modifier when using this feature. Unless you have the Spellcasting or Pact Magic feature, then your spellcasting matches with that feature(s). 

You are Resistant to Cold damage. Whenever you'd take Cold damage, you take less Cold damage equal to your Proficiency Bonus. 

Your Resistance to the Cold has become insurmountable. At character level 20, you become Immune to Cold damage. 

Your kind's cold and icy mind makes you sharper and more aware. If you lack Proficiency in Arcana, you gain Proficiency in Arcana. If you lack Proficiency in Survival, you gain Proficiency in Survival. If you lack Proficiency in INT, WIS, or CHA saving throws, you gain Half-Proficiency in those saving throws you aren't Proficient in. You also have Advantage on INT, WIS, and CHA saving throws. 

Your kind has an, additional but interesting way to heal. Whenever you're targeted by a spell that restores hit points, you can forgo up to 9 hit points healed to regrow your body parts, with it being 3 hit points per body part. At character level 8, you learn the Greater Restoration spell. It is always prepared and you can cast once every Short or Long Rest. You can cast it additional times using your spell slots if you have any or using your mana. But it must target either yourself or another Frostling. 

You know how to speak, but not like most beings. You know Primordial and the two dialects Aquan and Auran, Common Sign Language (CSL), and one more language of you choice that isn't Common or Undercommon.