Notes:

Calling Enslavers a "minor" Xeno feels kind of misleading, given that they were the cherry on top of the S--- Sandwich that was the War in Heaven, but that's just how cookie crumbles.

The Enslavers are neither Daemons nor Mortal creatures; but a strange mix of the two.

They originate from the warp, have psychic powers and feed on souls and spiritual energy like that of a demon. However, they reproduce like viruses, can starve to death and have an actual body with functioning organs; unlike a demon which does not really need them but has them because people think they should.

Chaos is complicated.

The Enslavers are responsible for the extinction of almost all of the life in the Galaxy following the end of the War in Heaven, with only the Orks, Eldar, Hrud and Jokaero surviving the onslaught. It's really no wonder that the Necrons took one look at this, declared "F--- It!" and went to bed for 60 million years.

As the name suggests, Enslavers take over peoples minds using their very naughty tentacles and slowly suck out their soul. Once the person is pretty much just an empty shell, the Enslaver lays eggs in their head which will then hatch after a year and quickly mature into adults.

I think you can see the problem here.

Just to make it clear though, here's a quote from Inquisitor Mallen describing the damage that just one Enslaver can do:

"Call them what you will--Krell, Psyrens or Enslavers. Just one witch, unsanctioned, caused the destruction of Hive Skorpios when one of those things used her brain as a gateway to this world. Within three days the entire hive’s population was reduced to drooling mindslaves. Within three weeks an entire continent was at war. And all because the governor thought his family should be exempt from the psyker cull and refused to give his daughter to the Black Ships."