We'll give it a try with those stats, and can always adjust later.
On to special abilities!Further, grave watchers have maximum hit points. This means a 5 HD grave watcher has 40 hit points, and a 15 HD grave watcher has 120.
Split (Ex): A full healed grave watcher of 10 or more HD can split into two grave watchers. The two new grave watchers may have any combination of HD that totals to the HD of the original grave watcher as long as they each have least 5 HD. This process takes 4 rounds and requires the grave watcher's concentration.Grave watchers which have 10 or more hit dice can split themselves in two. For example, a 10 HD grave watcher can become two 5 HD grave watchers. This process takes four rounds.
Fast Healing 2?(regenerating 2 hp a round);
Mesmerizing Lights (Su?): A grave watcher continually projects hundreds of tiny, pulsating lights, which are residual bursts of energy. These lights project illumination equivalent to a torch, and provide concealment (20% miss chance) for the grave watcher. Any creature viewing the grave watcher must succeed on a DC X Will save or become fascinated for 2d4 rounds. This is a mind-affecting compulsion ability. A creature that successfully saves cannot be affected again by the same grave watcher's mesmerizing lights for 24 hours. The save DC is Charisma(?)-based.A grave watcher looks like hundreds of tiny, pulsating lights -- a ballet of fireflies hovering over a grave or about a tomb. At any given time the lights are all the same color. However, the colors do vary from creature to creature, from white to rose to emerald green and shades in between.
The lights are not a part of the creature, but are residual bursts of energy that it constantly gives off. Some sages believe that the colors of the lights correspond to the creature's moods or strength. The lights effectively mask the creature, which is a black, vaguely man-shaped form with tentacles. The lights can also be distracting. Any characters viewing a grave watcher for the first time easily can become mesmerized by the light display. Such characters must make a saving throw vs. petrification at a -2 penalty or stand transfixed by the lights for 2d4 rounds.
Tentacle Growth (Ex): A gravewatcher has as one tentacle for each HD that it possessed over 4. However, these tentacles disintegrate and reform as the gravewatcher loses and regains hit points. For each 8+Con bonus (10 for an average gravewatcher) hp below maximum the gravewatcher possesses, the gravewatcher loses one tentacle. The tentacle regrows when the gravewatcher regains hp.For every 8 hit points of damage the grave watcher suffers, it loses one tentacle, and therefore one attack. Tentacles reform and reattach to the main body after four rounds (regenerating 2 hp a round); however, if a grave watcher's hit points ever fall below zero, the creature is slain.
It looks like we need a "join" ability to go with the split.Only one grave watcher has been noted at anyone time. Sages theorize that when multiple grave watchers come in contact with each other they fuse to form a larger creature.
It looks like the electricty from its tentacle attack could deal splash damage.A grave watcher only attacks if someone or something trespasses over a grave it has chosen to watch. A grave watcher has as many attacks as it has appendages. Each successful strike causes 1d8 points of electrical damage. In addition, if a struck victim is wearing or carrying more than 20 pounds of metal, the electricity has a scatter effect. All those standing within 10 feet of him suffer 1d8 points of damage from the electricity bouncing off of him (save vs. breath weapon for half). Please note that most metal armor weighs more than 20 pounds, and treasure often has a lot of metal in it.