When determining your character’s ability scores, increase one score by 2 and increase a different score by 1, or increase three different scores by 1. You can't raise any of your scores above 20.

You can speak, read, and write Common and one additional language of your choice.

You are a Beast.

Selphids are small enough to live in the stomach cavity of small and medium humanoids, your size is Tiny.

Your speed is 5 feet.

You can breathe air and water.

While not piloting a body, you are able to use your chemical reading of your immediate area.  You have blindsight out to a range of 5 feet. While piloting a body, you have an effective 0 feet of blindsight; instead, you gain any senses the creature had in life.

Selphids live in the abdominal cavity of corpses. During a long rest, you may spend your time acclimating and getting control of a small or medium humanoid corpse. While in a host body, you gain all of its senses, you count as its size, you use its movement speed, your true body gains complete cover, and it has your total hit point pool. Your host body does not get saving throws if you are reduced to 0 hit points and you lose all benefits of body snatch.

You can push your host body past its normal limit to achieve feats of physical prowess, but it permanently damages it. As a bonus action, you roll a d4 and reduce your host body’s maximum hit points by the amount.  Then choose to either increase your movement speed by 10 feet for 1 minute, add the d4 from before to your weapon or unarmed strikes for the three rounds, or add the d4 from earlier to your weapon or unarmed strike damage for the next three rounds. You can use this trait a number of times equal to your proficiency bonus, and regain all expended uses when you finish a long rest.

You are a pseudo-parasite that merely lives in the corpses of others, outside of a host body you are defenseless and vulnerable. Outside of a host body, your hit point pool is equal to your level and your AC is 8. You are immune to disease. If you are without a host body for an amount of hours equal to 8 + your constitution modifier, you die.