D&Dtools1

A blade made of pure negative energy appears and attacks opponents at a distance, as you direct it.
It strikes the opponent you designate, starting with one attack in the round when the spell is cast and continuing each round thereafter.
It strikes as a spell, not a weapon, so, for example, it can strike incorporeal creatures.
The blade attacks with your base attack bonus and bestows one negative level per hit.
It threatens a critical hit on a 19-20 and bestows two negative levels with a critical hit.
If the subject has at least as many negative levels as HD, he dies.
Each negative level gives a creature the following penalties: -1 competence penalty on attack rolls, saving throws, skill checks, ability checks, and effective level (for determining the power, duration, DC, and other details of spells or special abilities).
Additionally, a spellcaster loses one spell or spell slot from her highest available level.
Negative levels stack.
Assuming the subject survives, he regains lost levels after a number of hours equal to your caster level.
Usually, negative levels have a chance of permanently draining the subject's levels, but the negative levels from the sword of darkness don't last long enough to do so.
If the sword strikes an undead creature, it gives that creature 5 temporary hit points per two caster levels (maximum 25 temporary hit points) for 1 hour.
The weapon always strikes from your direction.
It does not get a flanking bonus or help a combatant get one.
Your feats (such as Weapon Focus) or combat actions (such as charge) do not affect the weapon, but your lack of proficiency does not hinder it either.
If the weapon goes beyond the spell range, if it goes out of your sight, or if you are not directing it, the weapon returns to you and hovers.
Each round after the first, you can use a standard action to switch the weapon to a new target.
If you do not, the weapon continues to attack the previous round's target.
On any round that the weapon switches targets, it gets one attack (as it does in the round when the spell is cast).
Subsequent rounds of attacking the same target allow the weapon to make multiple attacks if its base attack bonus would allow it to.
The sword of darkness cannot be attacked or damaged.
If an attacked creature has spell resistance, the resistance is checked the first time the sword of darkness strikes it.
If the weapon is successfully resisted, the spell is dispelled.
If not, the weapon has its normal full effect on that creature for the duration of the spell.
Material Component: A katana or long sword worth at least 100 gp, which is shattered against a stone while casting the spell.