Spectral Mobs

Specter Attacking in Limbo Dungeon

Spectral Mobs are most commonly found in Dungeons in pocket dimensions in the modDimensional Doors although are also found in the overworld underground water, or Limbo. The dungeons are a cobblestone structure that stands out from it's dimension.

They have a total of 12.5 hearts or 25 health on the Damage Indicators mod.

A Harbinger can spawn a spectral mob. When attacking a Harbinger, they spawn what appear to be smaller souls in a triangle or square formation. However, these are merely the disguised spawn forms of Spectral Mobs. Allowing a Harbinger to touch each one will spawn a spectral mob of a random type.

When attacking a Spectral Miner, you will have the Blindness Debuff for a while. 

Spectral Mob Eggs are all white with black spots.

Appearance

Spectre's look like Steve, except more ghostly and pale. They are often seen with chainmail armour and carrying a sword.

Other Spectral Mobs appear as all sorts of mobs, including wolves, creepers, and pigs. They can be characterized by their white, ghostly color palette.

Sounds

Spectre's make the same sound as endermen.

Behaviour

Spectres are hostile mobs that spawn by multiple spawners around their cobblstone home, they very commonly spawn in multiples and swarm the player with swords swinging.