Aranea

Shapechanger. The aranea can use its action to change between three forms. A humanoid form, a spider-humanoid hybrid, or back into its true form, which is a giant spider. Its statistics, except it's size, are the same in each form. It is medium in humanoid form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

Spellcasting. The aranea is a 3rd-level spellcaster. Its spellcasting ability is Charisma (spell save DC 12, +4 to hit with spell attacks). It has the following sorcerer spells prepared:

Cantrips (at will): dancing lights, mending, minor illusion, poison spray

1st level (4 slots): expeditious retreat, jump, silent image

2nd level (2 slots): invisibility

Sorcery Points. The aranea has 3 sorcery points. It can spend 1 or more sorcery points as a bonus action to gain one of the following benefits:

Quicken Spell: When you cast a spell that has a casting time of 1 action, you can spend 2 sorcery points to change the casting time to 1 bonus action for this casting.

Subtle Spell: When the kobold casts a spell, it can spend 1 sorcery point to cast the spell without any somatic or verbal components.

Spider Climb. The aranea can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Web Sense. While in contact with a web, the aranea knows the exact location of any other creature in contact with the same web.

Web Walker. The aranea ignores movement restrictions caused by webbing.

Bite. (Hybrid or Spider form only). Melee Weapon Attack: +5 to hit, reach 5 ft., one creature. Hit: 6 (1d6 + 3) piercing damage, and the target must make a DC 13 Constitution saving throw, taking 9 (2d8) poison damage on a failed save, or half as much damage on a successful one. If the poison damage reduces the target to 0 hit points, the target is stable but poisoned for 1 hour, even after regaining hit points, and is paralyzed while poisoned in this way.

Web (Hybrid or Spider form only, Recharge 5–6). Ranged Weapon Attack: +5 to hit, range 30/60 ft., one creature. Hit: The target is restrained by webbing. As an action, the restrained target can make a DC 12 Strength check, bursting the webbing on a success. The webbing can also be attacked and destroyed (AC 10; hp 5; vulnerability to fire damage; immunity to bludgeoning, poison, and psychic damage).