This scorpion is a normal giant scorpion with the Advanced simple template. It was constructed because several Paizo adventures (and at least one Pathfinder Society Scenario) references them.
Advanced Giant Scorpion CR 4
Sting—injury; save Fort DC 17; frequency 1/round for 6 rounds; effect 1d2 Strength damage; cure 1 save. The save DC is Constitutuion-based and includes a +2 racial bonus.
Grab: If this creature hits with a claw attack, it deals 1d6+6 damage and attempts to start a grapple as a free action without provoking an attack of opportunity. It may only grab Medium or smaller opponents. The centipede has the option to conduct the grapple normally, or simply use its claw to hold the opponent. If it chooses to do the latter, it takes a –20 penalty on its CMB check to make and maintain the grapple, but does not gain the grappled condition itself. A successful hold does not deal any extra damage.
Environment warm or temperate deserts, forests, plains, or underground
Giant scorpions are monstrous versions of the more common desert scorpion. They are likely to attack any creature that approaches. Giant scorpions usually charge when attacking, grabbing prey in their pincers, then lashing their segmented tails forward to kill their victim with injected venom.
Giant scorpions are just over 8 feet long from head to the base of the tail; the tail adds an additional 8 feet or so, although it is usually curled up over the scorpion’s back. Giant scorpions weigh between 2,000 and 6,000 pounds.
Giant scorpions normally feed on other giant vermin, as well as large mammals that they paralyze with their venom, but they will attack and eat any living creature that ventures too close. In turn, giant scorpions are preyed upon by purple worms and other large predators.
Giant scorpions engage in complex courtship rituals when they mate, grasping each other’s pincers, arching their tails, and performing a circular “dance.” Soon after mating, the male usually retreats to avoid being cannibalized by the female.
Female scorpions do not lay eggs; they give birth to live young in broods of a dozen or so. The mother carries her brood on her back until the young are old enough to fend for themselves and hunt their own prey.
Giant scorpions live in underground burrows, either as solitary hunters or in small colonies, and will sometimes take up residence in man-made ruins or dungeons if food is plentiful. Giant scorpion colonies are usually made up of scorpions from the same brood that have yet to strike out on their own.