You made a deal with an extraterrestrial. It promised you god-like powers, and you got them—at the price of your soul.
Barrier Effect: Contractors with the alien pact contract can push their bodies further within their barriers. While within your barrier, all forms of movement you possess are increased by 5 feet at 1st level, and an additional 5 feet at 5th level and every five levels thereafter, to +25 ft. at 20th level. This is an enhancement bonus. Additionally, you receive a +1 enhancement bonus to either Strength or Dexterity, chosen at 1st level, while inside your barrier. This bonus increases by +1 every time the bonus to your speed increases.
Contract Powers: The following are the granted powers of the alien pact contract.
Phylactery (Su): At 1st level, your alien sponsor has separated your soul from your body and placed it in a small magical item (such as a ring or pendant). As long as your phylactery is intact and within 100 feet of your body, you have regeneration 1/hour. This functions like normal regeneration, except that you only heal 1 hit point per hour with this ability. Your phylactery is under a constant nondetection effect with caster level equal to your contractor level. If it is destroyed or ceases to function (such as within an antimagic effect), you die. You can be revived as normal, but you lose all contractor class abilities until your sponsor recreates your phylactery (a special ritual costing 200 gp per contractor level and lasting one week). At any time that your soul is in your body, you lose all of your contract-specific abilities. Your phylactery does not occupy a body slot when worn.
If you and your phylactery are ever more than 100 feet away from each other, you lose control over your body and access to its sense perception. During this time, your body is, for all intents and purposes, a corpse. If left alone too long, it can decompose. If your body is destroyed while your phylactery is separated from you, your sponsor may attempt to contact someone to restore your body on your behalf, which requires magic similar to life-restoration. You can see and hear through your phylactery in a 30-foot radius at any time, but you cannot communicate or take any actions if your body is out of commission. Your sponsor always knows the precise location of your phylactery. One upside to having sold your soul to an alien is that your remuneration is considered paid—you need not restore your contract daily.
Undead Traits: At 4th level, your body runs entirely on the magic of your contract. You no longer need to eat, breathe, or sleep, and you gain immunity to sleep effects. At 8th level, you gain immunity to nonlethal damage. At 12th level, you gain immunity to paralysis and stunning. At 16th level, you gain immunity to death effects. At 20th level, you gain immunity to cold.
No Limits (Su): You can sap your body to power your contract. Once per day at 8th level, you may cast any contractor spell you know by taking Constitution damage equal to the spell's level * 2. This loss of Constitution cannot be mitigated by any ability or effect, and must be restored normally—it cannot be cured by magic short of wish or miracle. The spell cast does not expend any of your daily spell slots, but otherwise functions as though you were casting the spell normally. You may use this ability one additional time at 14th and 20th levels.
Dark Contract: At 12th level, add two spells to your list of spells known. These spells may be taken from any spell list, but must be of the necromancy school and be of a level equal to or lower the highest-level spell you can cast. At 16th level, add an additional two necromancy spells to your list of spells known.
Frightening Barrier: Your barrier is decorated with nightmare images and horrifying patterns. At 16th level, when a creature enters your barrier or is in its area when you expand it, that creature must make a Will save (using your barrier's DC) or become shaken. The shaken effect lasts until the creature leaves your barrier. If a creature succeeds on its Will save, it is immune to this effect for 24 hours. Allies and enemies are affected equally by this effect.
Avatar of Night (Su): At 20th level, the area within your barrier is supernaturally dark. You can still see in it, and your frightening barrier ability still takes effect, as the images are instead imprinted directly into the minds of your barrier's occupants. Additionally, you regain control of your soul. As long as your phylactery is in range, you can transfer your soul between your phylactery and your body at will with a 1-minute ritual. If your phylactery is destroyed while your soul is in your body, you do not die; however, you lose all class abilities except proficiencies until a new phylactery is constructed. As long as your soul is inside your phylactery, you ignore all age-related penalties to ability scores, your body cannot die of old age, and you gain blindsight 30 ft..