Byder

• Spider Climb. The Byder 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 Byder knows the exact location of any other creature in contact with the same web.
• Web Walker. The Byder ignores movement restrictions caused by webbing.
• Keen Smell. The Byder has advantage on Wisdom (Perception) checks that rely on smell.

Spellcasting. The Byder can cast the 2nd level spell Web twice per short rest. pertinent DC's equal 12.

• Multiattack. The Byder makes two attacks: one with its bite and one with its claws.
• Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one creature. Hit: (1d8 + 4) piercing damage plus (2d8) poison damage. The target must make a DC 12 CON save. On a failed save the target takes full poison damage and is considered poisoned, or half as much damage on a successful one, as well as not being poisoned. 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
• Claws. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: (2d6 + 4) slashing damage.
• Web (Recharge 5-6). Ranged Weapon Attack: +6 to hit, reach 30/60 ft, one creature. On a 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)

Attack of Opportunity:  The Byder makes one claw attack.