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.

Multiattack. Z'arach can make three melee attacks, only one can be bite. 

Frost Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one creature. Hit: (1d10)+2 piercing damage; and the target must succeed on a DC 12 Constitution saving throw or take (2d8) cold damage or take half damage on a successful save.

Leg Slash. Melee Weapon Attack: +8 to hit, reach 10 ft., one creature. Hit: (1d8)+5 slashing damage

Frozen Web. Ranged Weapon Attack. +8 to hit, range 30/60 ft, one creature. Hit: (8d6) cold damage and target must succeed on a DC 14 Strength check or be restrained by the webbing. If they fail three consecutive times, they suffer 1 point of exhaustion. Webbing may be attacked and destroyed. (AC: 10; hp 5; vulnerable to fire damage; immunity to bludgeoning, poison, and psychic damage)

Leg Slash (1 action): Z'Arach can use one of its legs to slash at a creature within 10ft. 

Web Pull (1 action): If a creature is caught in Z'Arach's frost web, she can use this action to pull it towards her up to 20 ft.

Cold Spray (2 actions, Recharge 5-6): Z'Arach sprays an icy mist from her fangs in a 60ft cone. Those within the cone take (8d8) cold damage or take half damage on a successful save.