Amphibious. The chimera can breathe air and water.
Spider Climb. The chimera 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 chimera knows the exact location of any other creature in contact with the same web.
Web Walker. The chimera ignores movement restrictions caused by webbing.
Multiattack. The chimera makes three attacks: two with its claws and one with its sting. When its web is available, it can use the web in place of its sting. The chimera may take a bite in place of a claw.
Claw. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 6 (1d8 + 2) bludgeoning damage, and the target is grappled (escape DC 12). The chimera has two claws, each of which can grapple only one target.
Sting. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 7 (1d10 + 2) piercing damage, and the target must make a DC 12 Constitution saving throw, taking 22 (4d10) 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.
Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one creature. Hit: 7 (1d8 + 3) piercing damage, and the target must make a DC 11 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 (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).
Description
A giant chimeric insect is a subtle combination of the giant variations of crab, scorpion, and spider. Upon first glance, it resembles a normal giant scorpion if a tad larger... Its stinger's poison has taken on the paralytic qualities of a giant spider's poison. It is amphibious and has many of a spider's special senses. It can shoot a spider's web through its tail.
with the attacks and versatility i feel like this should be CR 5 not 4
I guesstimated based off of the base monsters and comparing to other monsters of a similar level along with a middling armor class and health points a party of 5-7 adventurers @ level 4 w/ decent Con Scores should have around the same amount of health... If you want to use it for your own purposes you can remove the swim speed and amphibious traits and plop it down in a dessert or section of the Underdark...
oh, that seems reasonable, I've never had much of a foray into monster creation, i generally go by guesstimation most of the time