Arachnidkin were reduced by the gods for their crimes, as such, they grow up to 7 feet tall and only 5 feet wide at the arachnid portion.

You have a walking speed of 40 feet due to having 8 legs to carry you around.

Arachnidkin mature at around age 16 but can live up to 250 years of age if treated well

Arachnidkin tend towards chaotic alignmesnts and are generally more feared

Your dexterity increases by 2 and your intelligence increases by 1

You can speak read and write in common (or indercommon) and bug

You may lift up onto 6 legs as a bonus action, halving your movement speed, in order to perform a multi attack as an action, this does not allow you to take an extra attack, however. This multi attack involves you making an attack with a two handed weapon with which you are proficient, followed by two jabs with your newly free legs. The legs deal 1d4 piercing damage, with dexterity being the attack and damage modifier, you are proficient with your legs. You may use this ability the same number of times as your dexterity modifier per longrest.

you gain a climbing speed equal to your walking speed and you are not affected by difficult terrain

You gain proficiency with polearms if you do not already have proficiency. If you already have proficient with polearms, the damage dice doubles, as long with the proficiency bonus(e.g. Glaive damage goes from 1d10->2d10). 

As a bonus action, you may cast the web spell using no verbal, sematic, or material components. The dc for this spell is 8+your proficiency bonus+your dexterity modifier, unless you are a spellcaster in which the dc would be same as that dc.