You are a member of the Arachnoid guild of thieves, a powerfull guild based out of Everwinter. Although not all members worship the Spider queen, the leaders do and she gives the whole guild special abilities.

Spider Climb

At third level when you take this subclass you are always considered to be under the affect of the spider climb spell. Additionally spider webs impose no penalties on your movement or abilities.

Compound Eyes

At third level your compound eyes give you proficiency in perception, if you already have this proficiency you can instead gain proficiency in investigation.

Web Sling

A ninth level you gain the ability to use a bonus action or an action to sling a web at a wall, creature, or item. This webs have a normal range of your Dex mod*15 feet and a long range of twice that. When you do this you make a roll to see if you hit. The modifier to that equals your Dex mod + your proficiency bonus.

The DC to hit is determined by the DM but for guidelines you can use: DC 5 for walls and similarly large objects, DC 10 for support beams, tabels and other medium to large inanimate objects, DC 15 (or target AC) for smaller items such as books and living creatures though size may play a role. The affect of hitting depends on the general item type as listed below.

Once a relatively small, loose, inanimate object such as a book, table, treasure chest is caught by your web you can pull it up to 60 feet closer to you (no action required) as long as it is not heavier than your pull strength and all the ground on your way is solid, difficult terrain and pit traps on the way take twice the work to pull through.

If you hit a large, securly held object such as a wall, cave, or support beam you can use your movement to pull yourself closer to it. If the point involves you pulling yourself up your pull strength must exceed your weight including any equipment you have with you. If you end your turn in the air and diagonally from the point you are tethered to you automatically swing up to 60 feet or until you hit the ground/end directly under the tether point. During this time you remain the same circular distance from the tether point.

If you hit another creature you can make a web check as an action. A web check is an ability check using your Dex mod with which you a proficient and is contested by your opponents acrobatics or athletics (their choice). If you succeed your opponent is restrained and can use their action to try to break free forcing you to make another web check. During your next turn you can use a bonus action to attempt another web check to pull your target up to your movement closer to you or knock them prone.

Lines of web can be cut easily by any creature with any tool or weapon that is relatively sharp (no check required). A creature cannot do this if it is restrained by your webs.

You can also use this ability as a reaction when you are pushed of a cliff, fall down a pit trap, or are in any other way falling. When you use this reaction you make the room to hit your target with disadvantage and can choose to either pull someone with you (making all the rolls associated with pulling someone) or stick to a wall to save your self from falling.

While you are connected to anything using this ability one of your hands is focused on this, you do not need to drop whatever is in that hand but that hand can't use the item or preform any other action.

Spider Venom

Once you reach thirteenth level you can create spider venom in your mouth. Over a 10 minute period (during a short rest or just on you own time) you can create enough venom to make one of the following.

1: You create a vial of poison.

2: You apply the poison to a melee weapon which lasts for 1d4+1 hours and on hit deals and extra  2d4 poison damage and forces the target to make a DC 15 con save or be poisoned for 1 hour.

3: You apply the poison to a quiver/case of up to 20 pieces of ammunition which lasts for 1d4+1 hours and on hit deals and extra 2d4 poison damage and forces the target to make a DC 15 con save or be poisoned for 1 hour.

Spider Queen's Gift

At seventeenth level you can use an action to transform into a spider. While in this form you retain all class abilities and feats. In this form your AC equals 14 and you have a movement speed of 50 and a climb speed of 50. You are small enough to be left alone by guards and larger animals that dont hunt spiders, however guards with truesight will instantly notice this transformation.

While in this form you can climb on other creatures and try to do it without being notice on a successful disadvantage stealth check. All your equipment melds into your body while you are in spider form and you are 1 inch in all dimensions and weigh .5 pounds.

Your stats are as follows; Str 8, Dex 18, Con 6, mental ability scores are not changed. You have proficiency in stealth and anything provided by your class, feats, background, or race. You can take actions normal but your only attack action is a bite with +10 to hit that deals 1d1 piercing damage and has all the affects of your Spider Venom ability. If you are hit with an attack you immediately take you normal for and take damage as usual. You then fall prone in a spot within 5 of where you last were (dms choice where).