When a Sin-Eater manifests the Boneyard, he allows his geist’s plasm to flow forth from his body to stain the surrounding area with plasmic residue. In this way, the Sin-Eater may extend his senses across a large area and affect his environment in ways associated with the Key used to unlock the Boneyard.
Each boneyard is easier to use when the surroundings fit in with the used key (for example, the Cold Wind Boneyard is easier to use outside, but the Passion Boneyard is enhanced by locations infused with strong emotional resonance).
The Sin-Eater can bind or compel a ghost or spirit within his boneyard
By invoking the shades of the Underworld, the Sin-Eater can throw his victim into ennui and depression
The Sin-Eater can create a temporary Avernian Gate into the Underworld