Blood Frenzy. The spider has advantage on melee attack rolls against a creature that doesn't have all its hit points.

Death Smoke. When the spider dies, its body releases magical darkness that fills a 15-foot radius sphere centered on its body. The darkness spreads around corners and lasts for 1 minute. A creature with darkvision can’t see through this darkness unless it is a skeletal spider, and nonmagical light can’t illuminate the darkness.

Magic Resistance. The spider has advantage on saving throws against spells and other magical effects.

Spider Climb. The spider 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 spider knows the exact location of any other creature in contact with the same web.

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

Bestial Subtype. This creature is bestial, meaning the spells animal messenger, beast bond, beast sense, locate animals or plants, and speak with animals affect the creature as if it were a beast.

Multiattack. The spider makes two venom shot attacks.

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) piercing damage, and the target must make a DC 14 Constitution saving throw, taking 18 (4d8) poison damage plus 11 (2d10) necrotic damage on a failed save, or half as much damage on a successful one. If the poison or necrotic 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.

Venom Shot. Ranged Weapon Attack: +7 to hit, range 30/90 ft., one creature. Hit: 15 (2d10 + 4)  poison damage, and the target must succeed on a DC 14 Constitution saving throw or be poisoned until the end of the target's next turn.