An avalanche of gnashing teeth, bone hooks, and worm rolls forward in a wave of undulating parts. At the forefront of this thrashing, tentacled body yawns a howling pit of a mouth, ringed with a spiral of churning teeth and three massive, spiked mandibles.
AC 26, touch 11, flat-footed 23 (+3 Dex, +15 natural, -2 size)
Speed 40 ft., burrow 20 ft., climb 20 ft., swim 40 ft.
Str 32, Dex 16, Con 24, Int 8, Wis 16, Cha 20
An argorth can ascertain the location of all creatures within 120 feet. Beyond that range it is considered blinded, and must use other senses to locate creatures.
When an argorth is reduced to -24 hit points or lower, it collapses to the ground and thrashes wildly. It gets one final tail slam attack on every creature within 10 feet, after which it dies. It cannot grapple or constrict with this final attack.
An argorth can emit a wholly unnatural shriek, a howl not of the mortal world. When an argorth uses this ability, all creatures within 100 feet must succeed on a DC 21 Will save or be shaken for as long as the monster remains in sight. This is a sonic, mind-affecting fear effect. This ability does not affect creatures with more Hit Dice than the argorth. Whether or not the save is successful, an affected creature is immune to the same argorth's fearful shriek for 24 hours. The save DC is Charisma-based.
As a full-round action, an argorth can lift its entire body into the air and slam it against the ground in a single, reckless attack. This attack deals 1d10 points of damage to the argorth, but all creatures within 5 feet of the monster are targeted by a +13 melee attack which deals 2d8+16 points of damage. Any creature standing within 10 feet of an argorth when it makes this attack (including those who might be damaged) must make a DC 23 Reflex save or be knocked prone by the sheer force of the blow. The save DC is Constitution-based.
An argorth can always choose to take 10 on a Climb check, even if rushed or threatened. It can always choose to take 10 on a Swim check, even if distracted or endangered. It can use the run action while swimming, provided it swims in a straight line.