Your Constitution score increases by 2, and your Intelligence score increases by 1.

You gain proficiency in one skill of your choice, from: Acrobatics, Intimidation, Perception, Stealth, or Survival

As an attack action, an Arachne may bite a restrained creature with their fangs. Dealing 1d4 piercing damage and the creature must then make a Constitution saving throw (DC = 8 + proficiency ), becoming poisoned for 1d4 +1 round (scales at higher levels to 2d4 at level 5, )

Note: The DM rolls the poison D4 in secret.

Your creature type is considered to be both humanoid and monstrosity. this means you are considered a monster as well as being humanoid meaning normal races will perceive you as a monstrosity and run from you if not try to kill you. worlds events can even harm, negate, or advantage you, for example, the dm calls an event that all humanoids gain minus 2 strength and monsters gain plus 2 strength till the end of the event you gain noting because your humanoid and monster side are contrasting one another 

You have a climb speed equal to your walking speed. You can climb surfaces, including upside down on ceilings, without needing to make an ability check. Additionally, you ignore movement restrictions caused by webbing.

You can produce webbing from your spinneret glands a number of times equal to your CON modifier. The duration of the webs are indefinite but can be destroyed by normal means. A web has an AC of 15 and HP30 for each 10ft area of webbing and is vulnerable to fire damage. You regain the ability to make webbing after a short rest once you have exhausted your supply.

While in contact with a web made by her, the Arachne knows the exact location of any other creatures in contact with the same web.

While not wearing armor, the Arachne's AC calculation is 10 + DEX modifier.

You know how to speak, read and write Common, and Undercommon.

A medium or smaller creature can ride on your abdomen if you allow it. in such a situation you continue to act independently not as a controlled mount. unfortunately, you also cut you movent in half if it's a medium creature or by 10 if it's a small creature because you're not used to carrying large loads