Contortionist

Exceptionally flexible and nimble, you gain the following benefits:

• Increase your Dexterity score by 1, to a maximum of 20.

 While you are unarmored and unencumbered, you gain the following additional benefits:

• You can use your bonus action to dodge.
• You can move into a space occupied by another creature, regardless of its size, by succeeding on a DC 13 Dexterity (Acrobatics) check.  The creature can use its reaction to attempt to stop you, by making an opposing Dexterity (Acrobatics) check.*  If you succeed,  movement into the other creature's space counts as difficult terrain, and you must not end your turn in their space.  If you fail, your movement for the turn ends, and you are knocked prone.
• Standing from prone uses only 10 feet of movement, and while crawling, each foot of movement costs only an extra ½ foot of movement (1 foot in difficult terrain).
• You can squeeze into a space big enough for a creature up to two size categories smaller than you.

* First, declare your movement into the other creature's space.  Next, that creature decides whether or not to use its reaction to oppose your movement.  Finally, roll the Dexterity (Acrobatics) check(s).  To succeed, your total must be at least 13, and higher than your opponent's total (if you were opposed).