Classes:KnightGhost

From ZDoom Wiki

Ghost warrior
Actor type	Monster	Game
DoomEd Number	65	Class Name	KnightGhost
Spawn ID	129	Identifier	T_KNIGHTGHOST

Classes: Knight→KnightGhost

The ghost version of the undead warrior. Contrarily to its skeletal variant, all his attacks use the more powerful bloody axe rather than the usual ethereal axe, this difference in behavior is handled by the native action A_KnightAttack rather than by the actor's DECORATE code. Being a ghost, physical projectiles, such as the phoenix shot or the firemace's attacks, pass through him without causing any harm.

DECORATE definition

ACTOR KnightGhost : Knight 65
{
  Game Heretic
  SpawnID 129
  +SHADOW
  +GHOST
  RenderStyle Translucent
  Alpha 0.4
}