A vrock is about 8 feet tall and weighs about 500 pounds.

Vrocks are vicious fighters who like to fly down into the enemy and cause as much damage as possible. They prance about in battle, taking briefly to the air and bringing their clawed feet into play. Despite their advantage in mobility, the vrocks? deep love of battle frequently leads them into melee combats against heavy odds.
A vrock?s natural weapons, as well as any weapons it wields, are treated as chaotic-aligned and evil-aligned for the purpose of overcoming damage reduction.
Dance of Ruin (Su): To use this ability, a group of at least three vrocks must join hands in a circle, dancing wildly and chanting.
At the end of 3 rounds of dancing, a wave of crackling energy flashes outward in a 100-foot radius. All creatures except for demons within the radius take 20d6 points of damage (Reflex DC 18 half ). Stunning, paralyzing, or slaying one of the vrocks stops the dance. The save DC is Charisma-based.
Spell-Like Abilities: At will?mirror image, telekinesis (DC 18), greater teleport (self plus 50 pounds of objects only); 1/day?heroism. Caster level 12th. The save DCs are Charisma-based.
Spores (Ex): A vrock can release masses of spores from its body once every 3 rounds as a free action. The spores automatically deal 1d8 points of damage to all creatures adjacent to the vrock. They then penetrate the skin and grow, dealing an additional 1d4 points of damage each round for 10 rounds. At the end of this time, the victim is covered with a tangle of viny growths. (The vines are harmless and wither away in 1d4 days.) A delay poison spell stops the spores? growth for its duration. Bless, neutralize poison, or remove disease kills the spores, as does sprinkling the victim with a vial of holy water.
Stunning Screech (Su): Once per hour a vrock can emit a piercing screech. All creatures except for demons within a 30-foot radius must succeed on a DC 22 Fortutude save or be stunned for 1 round. The save DC is Consitution-based.
Summon Demon (Sp): Once per day a vrock can attempt to summon 2d10 dretches or another vrock with a 35% chance of success. This ability is the equivalent of a 3rd-level spell.
Skills: Vrocks have a +8 racial bonus on Listen and Spot checks.

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System Reference Document -> List of Creatures (SRD)