Your Strength, Constitution, and Dexterity scores increases by 1

You age the same rate as Yuan-Ti Purebloods and can live slightly longer.

Abominations can vary between the size of a human to 8-10ft long if they are mostly snakelike. Your size is medium but you count as one size larger when determining carry weight.   

The muscular body of an Abomination makes them very quick on land and in water. Your base walking speed is 35, you also have a swimming and climbing speed of 30.

You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can't discern color in darkness, only shades of gray.

You know the Poison Spray cantrip. You can cast Animal Friendship an unlimited number of times with this trait, but you can target only snakes with it. Starting at 3rd level, you can also cast Suggestion with this trait. Once you cast it, you can't do so again until you finish a long rest. Charisma is your spellcasting ability for these spells.

You have advantage on saving throws against spells and other magical effects.

You are immune to poison damage and the poisoned condition.

As an action you make a strength based unarmed attack with your tail, on a hit you deal 1d6+STR modifier bludgeoning damage and  grapple the target, they then enter your space. As an action on their turn the grappled target can make a Strength(Athletics) or a Dexterity(Acrobatics) check against you to escape. Until this grapple ends, the target is considered grappled and restrained, and gets pulled into your space. While constricting you can't constrict another target, and your movement speed becomes 0.

You can speak, read, and write Common, Abyssal, and Draconic.

The Yuan-Ti Abominations' creature type is Monstrosity.  

As a cold blooded serpent you are susceptible to cold weather. You make ability checks and saving throws to resist the effects of cold weather at disadvantaged.