Soul Shards are a unit of measuring Anima, or the essence contained within souls. One soul shard does not equal one human soul--its a far smaller quantity, and in any case, not all souls have the same amount of Anima. The Shard is a useful atomic unit, the smallest significant portion of Anima that can be put to use.
You can acquire Soul Shards in several ways:
Your own soul is worth (5 + Cha) x level soul shards. You can spend from your own soul freely, but if you ever possess less than half of your own total, you are vulnerable to control by extraplanar entities, and at 0, you are helpless to resist them.
You can drain soul shards from other creatures with various warlock powers.
Each time you convince an individual with a soul to sin, you gain an amount of shards commensurate with the intensity of the sin (1 for a minor venial sin, 5 for a clear mortal sin, more possible in extreme cases).
You can spend Soul Shards in several ways:
Most powers can be empowered by spending shards, as specified in the power's description.
There are some general uses for shards (TBD)
Corruption
Certain temporary abilities from your powers that cost soul shards can become permanent, not requiring them, although it comes at a cost, twisting your mortal form into one more suited to your increasingly extraplanar nature.
Reduce a target's HP to half (or 1 with empowerment)
Ideas
Faceted Powers
Powers that do essentially the same thing but are flavored based on your favored pact.
Short-range Teleport:
Fey Step
Shadow Jump
?
Armor:
Fel Armor
Chromatic Shield
Armor of Darkness
Eldritch Blast:
Immolation
Jubilation
Corruption? or just Shadow Bolt
Feats
Infernal
Demon Claw: As a swift action, your hands transform into demonic claws, which can be used as a Str or Dex melee attack inflicting heavy slashing damage. You gain your Charisma bonus to grapple checks with said claws.
Devil's Eye: See the unseen, blast enemies with cool eye lasers
