Glow Spider

Appearance: Black body with lime-green, eyes, spots, and spinnerets. The green parts of them would glow like the spots of a glow squid. The overall effect would give them a creepy-cool look. If a quirky aspect is needed, I would suggest having the spots on their back arranged like the buttons on a sheared snow golem's face.

Combat: Would attack similarly to spiders and cave spiders. The difference would be that they would give the player a paralyzing effect, rather than the cave spider's poison. I would suggest weakness, since witches are the only mobs capable of giving it to the player currently, but slowness could work as well.

Uses: They would drop glow silk and normal spider eyes. Glow silk could be crafted into string, glow silk webs, and potentially interesting light sources and other items.

Habitat: They would spawn in darker caves, most commonly in ones with glow silk on the walls. Their habitat would help emphasize their eerie appearance.

Reasons for this mob: It would add a unique new enemy to caves, both combat and appearance-wise. Their glow silk webs would make an interesting decoration and would add to the spooky feel of caves. In addition, they would add an extra reason for enchanting weapons with Bane of Arthropods.