Arachules

A black spider born of the spider god to be a mortal fighter along the back of the god's chosen hero. It will grow and fight with the hero and gain powers depending on the hero's level (1 power per 2 levels). To use abilities the spider requires time to rest and recharge it webs and poison. Regains (1/2 player level)d4 charges per long rest, and gains more based off the CR of creatures that die to poison damage. Number of charges is equal to player level

1. Spider Pack (Passive)
   +2 ac to any creatures attacking the wearer from the back.
   Spidered Arrow (only up to 5 per long rest) (No cost)
   On hit the arrow will deal an additional 2d12 poison damage on a failed con DC 15 save (Half on a successful) and the target will need to make a dex DC of 15 or be webbed. If target does not break free of the web (Str DC of 15), they take an additional 1d8 damage per round.
   Slick with Poison (Reaction to shooting) (1 charge)
   On firing an arrow the spider takes a reaction to spit poison onto the tip. Target must make a cons DC of 15 or take 2d12 additional poison damage (Half on a successful) and a cons DC of 5(+1 per level) or become vulnerable to poison.
2. Set Trap (1 minute) (4 charges)
   Create a spider trap up to a 20 foot area and determine it's Trigger and reaction. The Trigger can be anything from touching a specific book on a book shelf. Opening a door, or just walking over an area. The Reaction can either be track, web, or attack. Track will have a single spider crawl onto the target and be able to be tracked by the owner. Web will cast a strong web with Str DC 18 to any in the area, or the one target (Depending on the size and trigger). And attack makes the spiders attack, dealing 3d8 poison damage on a cons DC of 18 (Half on a successful) to all in the area, or one target, depending on the trigger.
3. Fang Shot (1 action) (2 charges)
   The spider shoots poison up to 90 foot from it's fang to a target. +6 to hit. On a hit the target must make a Cons save of 16 or take 2d12 poison damage and be blinded (Half on a successful, and not blinded). Each turn after a failed save, target must make another cons save of 15 or take 2d6 poison damage and still be blinded.
4. Toxic Smite (Reaction to hit) (4 charges)
   Smite the target with  3d12 poison damage instantly with a Cons DC 16 (Half on a successful).
5. Poison Rain (1 action) (4 charges)
   The spider spit out a hail of Poison in a 30ft radius up to 90 foot away. All creatures in that area must make a DC Cons save of 14 or take 2d12 poison damage (Half on a successful)
6. Blob of Poison (1 action) (6 charges)
   The spider lobs a blob of poison to a target within 20 foot dealing 4d12 poison damage on a failed cons DC save of 18 (Half on a successful).
7. Spider Breath (1 action) (10 charges)
   The spider breaths out a 30 foot cone of acid. DC cons save of 18 or take 3d12 poison damage (Half on a successful).
8. Spider-egg Arrow (1 created per long rest)
   Shoot to spawn several spiders in a 20 foot area. They can't move from that area, but any creature in that area, entering that area, or ending their turn in that area must make a cons and strength save of 16 or be poisoned dealing 2d12 damage on a failed cons save (Half on a successful) and be webbed on a failed strength save. Lasts 1 minutes before spiders all run away.
9. God's Web (1 action) (15 charges)
   The spider shoot a web in a 30 foot area. Str DC of 18 or be caught in it. Must make this check again at the start of each turn to break free. If caught in the web, Cons DC of 20 or take 4d12 poison damage and the end of their turn.
10. True form (1 minute) 
    Turn yourself into a Drider for 1 hour. Doubling poison damage dealt. Gaining 40 charges of poison. +10 to dexterity. Each arrow is a Spidered Arrow. Spiderclimb as a free action. Gain +4 ac, you are now considered 1 size larger. All above spider powers that take 1 action can now be cast as a bonus action.