By Alan McCoy from Dungeons & Dragons: Fundamentals
How to build challenging encounters against a Giant Scorpion
Note: This has been prepared utilizing only the 5E Core Rules. The Giant Scorpion can be found in the Monster Manual page 327.
Giant Scorpions are essentially gargantuan versions of their tiny natural cousins. Large, they are roughly five feet long and weigh several hundred pounds. Their claws and tail extend this overall size to make them equivalent to the size of mass of a horse.
Giant Scorpions are usually magically created guardians or remnants of horrible experiments on normal creatures. In cases where such creatures are found in the wild, they can breed and perpetuate their giant versions of their species provided sufficient food is available.
Giant Scorpions subsist on essentially any prey smaller than they are, they can consume refuse, they are carnivores, not omnivores.
Because of their extremely virulent poison, the giant scorpion is quite dangerous and if detected in civilized lands, will require immediate action from the authorities.
Step 1) Let’s Review what we know about the Giant Scorpion:
These creatures are extremely fast, especially considering their size, moving at 40 feet per round.
The Giant Scorpion is extremely strong and tough and has above average dexterity. Mentally, the creature has a vestigial intellect and almost no sense of self. It operates almost exclusively by instinct and sense of self preservation.
The Giant Scorpion has BLINDSIGHT 60 feet, and a Passive Perception of 9.
Step 2) Determine the probable Strategy.
Giant Scorpions do not have a strategy per se. Instead they have instinctual hunting methods that have been programed into them. Their instinctual hunting method is to hide in the light, hunt in the dark, isolate and grab their prey, grapple, and inject venom. Move away and into the darkness to feed at their leisure.
Because a Giant Scorpion prefers prey that are more easily consumed, it will avoid those in ‘shells’ (armor) and instead focus on softer prey.
Step 3) Determine Tactics
While the Giant Scorpion is unintelligent, it does have instinct and a prey preference. Like most ambush predators, it wants its prey at a disadvantage, preferably blind and unable to detect its approach.
To accomplish this, it hunts at night, or in darkness. It chooses an isolated prey animal, stings, injects its venom, then uses its high rate of speed to allow it to grab the prey and dash away to consume without distraction.
Because the Scorpion has no stealth skill, it utilizes darkness and concealment to hide itself while it waits for a prey animal to approach. When the target is within range, it will immediately try to sting, then grab with its claws.
The giant scorpion is unintelligent, and the presence of others with the prey animal will not deter its attack.
The Giant Scorpion has MULTIATTACK and can use two Claw attacks and one STING attack each round. The Claw attacks can grapple an opponent subjecting it to the grappled condition. A claw that is grappling an opponent may not be used to attack another.
Step 4) DM Tips and Observations
A creature’s primary sense ability should always be capable of allowing it to see well enough to accomplish a DASH. Therefore, I believe that the BLINDSIGHT ability of the Giant Scorpion should be 80 instead of 60.
A target caught in a Giant Scorpion’s Claws should be subject to the RESTRAINED condition instead of the GRAPPLED condition. The creature is trying to hold you still so it can inject venom, it will take you way once you are incapacitated or dead.