Monks who have studied the actions of spiders and have learned to weave their Ki as spiders do their webs or those taken into a Lolthite cult will learn how to cultivate and manifest their inner spider.

Arachnid Constitution

3rd-Level Way of the Silken Spider Feature

You have adapted your body to better fit your arachnid ideal.

Arachnid Body. You have gained resistance to poison.

Arachnid Strike. Your unarmed strikes may now deal poison damage in addition to its normal damage types.

Skills of the Spider

3rd-Level Way of the Silken Spider Feature

You may spend 2 ki points as an action to cast the Web spell.

Also, you may spend 1 ki point as an action to be as if under the effects of the Spider Climb spell for 1 hour.

When you reach 9th level in this class you may always be under the effects of Spider Climb without spending Ki points.

Generate Venom

6th-Level Way of the Silken Spider Feature

Once per turn, when you deal poison damage, you force the recipient to roll a CON save or take additional poison damage equal to 2 rolls of your Martial Arts die and be poisoned until the end of their turn. A target poisoned this way cannot be targeted by stunning strike but if they are already stunned that status remains as normal.

At 11th level, the damage of this feature increases to three rolls of your Martial Arts die and ignores poison resistance.

You can use this feature a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.

Aspect of the Spider

11th-Level Way of the Silken Spider Feature

As a bonus action you can enhance your inner spider for 1 minute. You grow 4 extra limbs reminiscent of a spiders as well as other spider features you desire and have the following benefits:
Arachnophobia. When you change in this way, you can force a number of creatures up to your proficiency who can see you to make a WIS saving throw or become frightened of you for 1 minute. The target can repeat the saving throw at the end of each of its turns.

Eight-Legged Flurry. When you flurry of blows you gain a third strike.

Protection of the Brood. If you would be reduced to 0 health while this feature is active you may pay 2 Ki points as a free action to discorporate into a swarm of spiders and move up to your movement away from the damage dealer without provoking attacks of opportunity. You then reincorporate, this feature ends and you are at 1 health

Once you create this aura, you can’t create it again until you finish a long rest, unless you expend 3 ki points to create it again.

Arachnid Incarnate

17th-Level Way of the Silken Spider Feature

You and your inner spider are as one. You gain the following benefits:
Venomous. When you use Generate Venom, you can spend 1 ki point to augment it. The save is either made with disadvantage or your opponent’s immunity to poison is ignored (your choice). Target creature takes 4d10 damage on a failed save.
Tremorsense. You gain tremorsense out to 60 ft. Within that range you can see anything even if you're blinded or in darkness. You can also see invisible creatures unless it successfully hides from you.
Web Weaver. When you activate Aspect of the Spider, as part of the activation you can create a web, as the spell Web, for free centered on yourself. You are unaffected by the spell for its duration.