Ethereal

Ethereal (sometimes called Ghost or Decrepify) is a type of status effect that makes the target immune to physical damage while also being unable to attack. Afflicted units can still cast spells, but will also take additional magic damage.

Ethereal units cannot be targeted by physical attacks, even manually-cast Unique Attack Modifiers such as Arcane Orb. They will also not take damage from any spells that deal physical damage, although they will still be affected by secondary effects of those spells, such as disables. Becoming Ethereal will also remove certain buffs.