Spider Bone Golem CR: 8
Large construct, neutral
Armor Class: 15 (Natural Armor)
Hit Points: 200 (20d10 + 100)
Speed:
40 ft
, climb: 40 ft
STR
20 +5
DEX
10 +0
CON
20 +5
INT
3 -4
WIS
5 -3
CHA
2 -4
Saving Throws: STR +8, CON +8
Damage Resistances: Cold, Fire
Damage Immunities: Poison; Bludgeoning, Piercing, and Slashing from Nonmagical Attacks that aren't Adamantine or Silvered
Condition Immunities: Charmed, Exhaustion, Frightened, Paralyzed, Poisoned, Stunned, Unconscious
Senses: Darkvision 30 ft, Tremorsense 120 ft, Passive Perception 10
Languages: Understands the languages of its creator but can't speak
Challenge Rating: 8
Many eyes. The golem has advantage on Perception checks that rely on sight. Magic Resistance. The golem has advantage on saving throws against spells and other magical effects. Magic Weapons. The golem's weapon attacks are magical. Poison Marrow. Whenever the golem is subjected to poison damage, it takes no damage and insteadregains a number of hit points equal to the poison damage dealt. 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.
Actions
Multiattack. The golem can make 1 bite attack and 2 Spindle leg attacks or the Sider can use its poisoned web and 1 bite attack. Bite. Melee Weapon Attack: +8 to hit, reach 5 ft., 1 target. Hit: 11 (2d6 + 5) [piercing] damage plus the target must make a DC 15 constitution saving throw or take 2d6 poison damage. Spindle Leg. Melee Weapon Attack: +8 to hit, reach 10 ft., 1 target. Hit: 9 (1d8 + 5) [piercing damage] damage. Poisoned Web (Recharge 5–6). Ranged Weapon Attack: +3 to hit, range 30/60 ft., one creature. Hit: The target is restrained by webbing. At the beginning of the target's turn, they must make a Constitution Saving throw or take 3d6 poison damage. As an action, the restrained target can make a DC 16 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).
The Spider Bone Golem appears to be an amalgamation of bones fused together to create a ten-foot-tall spider, light and deadly.