This creature is a massive reptilian beast with four stump-like legs and a multitude of heads surrounding a central maw filled with oversized teeth. Its body is reddish-gold and scaled. A long serpentine tail extends from its body and ends in a pincer-like claw.
Speed 40 ft., swim 20 ft.
Str 27, Dex 12, Con 24, Int 2, Wis 10, Cha 9
A thessalmonster with a tail can grab an opponent up to one size smaller with a successful tail slash attack. It can then attempt a grapple check as a free action without provoking an attack of opportunity. If it wins the grapple check, the thessalmonster establishes a hold and can constrict.
Though a thessalmonster cannot be killed by severing all of its serpentine heads, doing so prevents them from attacking and can assist in slaying its body. Any attack that is not an attempt to sever a head affects the body, including area attacks or attacks that cause piercing or bludgeoning damage. To sever a head, an opponent must make a sunder attempt with a slashing weapon targeting a head.
A head is considered a separate weapon with hardness 0 and hit points equal to the thessalmonster’s HD. To sever a head, an opponent must inflict enough damage to reduce the head’s hit points to 0 or less. Severing a head deals damage to the thessalmonster’s body equal to the thessalmonsters’s current HD. A thessalmonster can’t attack with a severed head, but takes no other penalties.
A thessalmonster that does not already possess a breath weapon or spit type special attack can spit a stream of acid in a 40-foot line that deals 4d6 points of acid damage. A successful Reflex save reduces the damage by half. This acid originates from the thessalmonster’s primary head or central maw and can be used once per day.