Hellsaw Symbiote (3.5e Monster)

You encounter a stubby short creature with spidery legs, a vicious vertical aligned jaw on one end, and and the presumed front end which is dominated with a large bladed snout like a swordfish, but thicker and containing an array of sharp teeth which vibrate back and forth at high speed like some kind of chainsaw.

A biological weapon crafted by mad devil scientists, the hellsaw symbiote is a living chainsaw which bites off the arm of a creature and replaces it with a whirring blade of death. Bone and flesh instead of metal and wood, its fuel is blood and its oil is hate. They are dull witted but just as evil as any devil, enjoying cutting through soft, innocent flesh. Hellsaw symbiotes are roughly the size of a chainsaw and they weight 20 lbs. They do not speak but roar with the sound of their distinctive buzz.

Combat
Hellsaw symbiotes like to prey on weakened creatures on the battlefield, using their buzzing hellsaw teeth to drop creatures that would resist, and attaching to the arm. If the creature is strong enough to take the damage and survive, it will prove an effective host. If it binds to a creature which is not lawful evil, it will emphatically nudge the creature towards lawful evil acts, or in more extreme cases attempt outright domination every round.

Disruptive Field : An aura which radiates in a 10 foot radius out from the menos disrupts the flow of magic, psionics, and any other spell or spell-like ability. Any attempts to cast within one automatically fail as if they failed a Concentration check to cast defensively. It is not an antimagic field, and so magical effects originating from outside the field can still get in.

Empathy : Hellsaw Symbiotes do not have telepathy, but they do have empathy out to 30 feet.

Extraordinary Health : A menos always recieves maximum hit points per hit die.

Grind : Hellsaw symbiotes buzz like a living chainsaw, allowing them to bypass damage reduction easier. Add the damage of all the attacks made by the hellsaw (typically when connected to a host with a high enough BAB). Apply damage reduction or hardness only once to the total damage caused by all the attacks which hit. The hellsaw counts as lawful, evil, and magic for bypassing damage reduction.

Hinder Magic : All magical damage or healing is hindered by 50%.

Life Drain : Any successful attack against a living creature deals at +1 extra damage (already accounted for), which is absorbed as 1 point of healing per attack.

Maneuver-Like Abilities : blitzkrieg (strike), glasscut breaker (strike), masque of red death (boost), overenthusiastic parry (counter)

Smell Magic : Hellsaw symbiotes have scent against anything which would show up with detect magic and may spend three rounds studying the scent to gain information as per the spell.

Symbiote : A hellsaw acts a symbiote, enabling it to connect to a willing or helpless creature as a full-round action. It clamps its mouth (which is on its apparent back side) around one of the victim's arms, severing it and binding to the fresh wound. This deals 1d6 Constitution damage. From this point the arm is worthless, but the creature can use the symbiote as a manufactured weapon grafted right to the limb, dealing 1d8+5 damage plus your strength modifier. The hellsaw is capable of being enhanced like a normal manufactured weapon, and you gain the Disruptive Field, Feats, Grind, Maneuver-Like Abilities, and Life Drain abilities of the symbiote. It functions as an intelligent weapon and can attempt to dominate its wielder (as dominate monster) with a DC 14 Will save if the wielder acts against the weapons wishes, which is generally to engage in as many combats as possible and feed it blood. The save DC for the domination effect is Charisma based.

While bound to a creature the symbiote is treated as an attended weapon, not a creature. It its host dies, it detaches and attempts to hook with another, stronger creature. Creatures one step away from its alignment (LE, LN, and NE) generally are tolerated, while creatures two steps away (LG, TN, and CE) are subject to domination. CG creatures are subject to domination and take 2 negative levels while they are bound to the symbiote.

Hellsaws as treasure
If you give your players an opportunity to bond with a hellsaw, its approximate item value is 12,000 gp. Deduct this amount from their expected wealth gains.