The main problem with a LA +0 ghost template (or even a low LA ghost template) are the bonuses gained via the Undead type and the Incorporeal subtype. Those two together grant:
Undead
- 12 sided HD
- no Con score
- Dark Vision 60 ft
- Immunity to all Mind Affecting Effects (charms, compulsions, phantasms, patterns, and morale effects)
- Immunity to Death Effects, Disease, Paralysis, Poison, Sleep effects, and Stunning.
- Not subject to Critical Hits, Nonleathal Damage, Ability Drain, or Energy Drain. Immune to damage to its Physical Ability Scores as well as Fatigue and Exhaustion effects.
- Immune to any effect that requires a Fortitude save (unless the effect also works on objects).
- Uses Cha for Concentration checks
- Not at Risk of Death from Massive Damage, but when reduced to 0 hp or less it is immediately destroyed (some exceptions exist).
- Not affected by Raise Dead and Reincarnate spells or abilities. Resurrection and True Resurrection can return undead back into the living creatures they were prior to becoming undead.
- Proficient with all natural weapons, simple weapons, and any weapon mentioned in its entry.
- Undead to not breathe, eat, or sleep.
Incorporeal
- can only be harmed by other incorporeal creatures, magical weapons, or creatures that strike as magic weapons, and spells, spell-like abilities, or supernatural abilities.
- Immune to all non-magical attack forms. Even when hit by magical weaponry ther is a 50% chance to ignore any damage from a corporeal source (except positive energy, negative energy, force effects, and attacks made with ghost touch weapons).
- no natural armor bonus, but gains a deflection bonus equal to its charisma modifier (always at least +1)
- can pass through solid objects but must remain adjacent to the object's exterior, so it cannot pass entirely through an object whose space is larger than its own. It can sense the presense of creature or objects within the square adjacent to its current location, but enemies have total concealment (50% miss chance) from an incorporeal creature inside an object. In order to see normally and attack normally it must emerge. An incorporeal creature inside an object has total cover, but when it attacks a creature outside the object it only has cover. An incorporeal creature cannot pass through a force effect.
- attacks ignore / pass through natural armor, armor, and shields, although deflection bonuses and force effects work normally against it.
- can pass through and operate in water as easily as they do in air.
- cannot fall or take fall damage
- cannot be grappled or tripped, but cannot make grapples or trip attacks
- cannot take any physical action that would move or manipulate an opponent or its equipment, nor subject to such attacks (bull rush, overrun, disarm, trip, grapple, etc)
- do not set off traps triggered by weight
- moves silently and cannot be heard with Listen checks unless it wishes to be heard
- has no strength score, so its Dexterity score applies to both melee and ranged attacks
- nonvisual senses such as scent and blindsight are either ineffective or only partly effective in regards to incorporeal creatures
- have an innate sense of direction and can move at full speed even when they cannot see.
Collectively, these are a lot of bonuses. Consider for a moment a ghost Rogue 3/ Assassin 3/ Soulknife 7; this is a potent opponent. Actually, the ghost has a racial bonus of +8 to Hide and Move Silently, so I'd state that all it needs is the +4 to Disguise and Any Evil alignment to qualify for Assassin. So one level in rogue, followed by three levels in Assassin and seven levels in Soulknife, and you have a really impressive threat - +3d6 sneak attack, a couple levels of assassin spells, +2d8 psychic strike, +2 mindblade, throw mindblade, two mindblade or a greatsword mindblade, +2 equivalent enhancement to mindblade (unholy or bane, for instance), uncanny dodge, Speed of Thought, perhaps a couple psionic feats, and the various bonuses for being undead and incorporeal.
That's worth the LA +5 (or the CR +2), in my opinion. It is certainly a worthy threat for a 13th level party - and it might be able to hold its own as a member in a 16th level party. Of course, I'd probably utilize a form of LA buyoff from UA, such that it would only a be LA +4 by then - and perhaps a level behind but nearly entirely catching up. From that perspective its inability to completely hold its own at that level (as a PC) would be understandable, as it would be a 15th level character in a 16th level group (but it would be quickly catching up).
To reduce the cost for the ghost template, I suggest the following: remove the Undead type, remove the ability to interact with objects at all (that is to say, the ghost also has a 50% chance of causing no damage on a hit, rather than just the ghost having a chance of receiving no damage from a hit). Make the bonus to Cha reflect the deflection bonus regardless of its score (thus no auto +1 deflection, and a negative deflection - ie: easier to hit - with a negative Cha bonus), and remove its innate senses a) of direction (such that its speed is reduced when it cannot see) and b) of creatures / objects outside of an object - such that it cannot surprise attack creatures just beyond the edge of the wall, for instance, as it would not know any creatures were present unless it emerged.
In effect, it becomes a semi-ethereal creature that - not being undead - can be affected in a variety of ways if the attack can actually connect (poison, disease, paralysis, stunning, sleep, ability damage, energy drain, etc). It would have a Con score, as it would be alive and have a body on another plane, and it would have a Str score, although the score would be considered '---' when fighting creatures on the physical plane. On the plus side this would allow it to have feats such as Power Attack. On the negative side, it could only use such feats against creatures on the same plane as it (the Ethereal). Allow the ghost to manifest, perhaps, or possess, but it cannot have any other specials.
That, I think, would reduce the LA to only +1 or maybe +2. The CR would perhaps end up as either +0 or maybe +1.
