- Main article: M'uru (tactics)
|Race||Void god (Demon)|
|Location||Shrine of the Eclipse, Sunwell Plateau|
- This appears to be the "void" that the naaru transform into upon death. Although the other darkened naaru ( and ) have not become void beings, this might be the result of M'uru being drained by the Blood Knights.
- Entropius also appears as a "memory" summoned in the Trial of the Champion.
- The name "entropius" is likely a derivation of "entropy", the amount of energy unavailable to perform work on a system, commonly construed to mean the level of "disorder" or "chaos" in a system. Entropy is also defined as the state in which all objects are moving toward a higher level of disorder.
- Patch 2.4.0 (2008-03-25): Added.