Collecting
Obtained: 10,000 Khyber Dragonshard Fragments
Becomes: 100 Tiny Khyber Shards (10 HD)
Becomes: 20 Small Khyber Shards (20 HD)
Becomes: 8 Average Khyber Shards (30 HD)
Casting 20-HD version of Trap the Soul
Earth Elemental (CR 5): Weak Essence of Earth
Earth Elemental (CR 7): Essence of Earth
Fire Elemental (CR 7): Essence of Fire
Earth Elemental (CR 10): Immune
Air Elemental (CR 11): Immune
Ghaele (CR 16): Essence of the Rebel
Casting 30-HD version of Trap the Soul
Air Elemental (CR 11): Strong Essence of Air
Placing Soul Essences on Eldritch Machine
Essence of Earth: fits in slot
Weak Essence of Earth: rejected by slot
Others: rejected by slot
Placing Soul Essences on Altar of Fecundity
All rejected.
Note1: By the monster manual, Elementals generally have HD about twice their CR. Outsiders, such as Devils and Eladrins, have HD about CR +/-2.
Note2: Apparently, Air Essences below Strong do not exist in DDO.
A warning: Many outsiders like Devils and Eladrins have Spell Resistance. To avoid wasting Kyber Shards, be sure to pick up a Spell Penetration VIII item before casting Trap the Soul on them, and hire an assistant to club it with Shattermantle. Whenever possible, target a no-SR outsider of the desired alignment, such as an Efreet instead of a Devil.