Astral

Astral is the term for Familiars who do not possess a physical form. Most Astral familiars are from the Necromancy tree. As they are of intangible form, Astral familiars are generally immune to Substance based attacks and debuffs, but they cannot be healed except by using an Obelisk. Astral familiars are also particularly vulnerable to anti-Astral units, such as Skullmage or Unicorns with Astral Hold

List of Astral Familiars

 * Fairy (if they use Astral Change)
 * Morning Star
 * Ghost
 * Phantom
 * Charon
 * Units that receive the Skullmage's Astralize