Enslavers are among the most hated creatures in Equestria - by changelings. No-one knows for sure where they came from, but it is rumored they evolved from changelings who were driven out of their hive - loners who were forced to come up with new tactics.
Without a hive to fall back on, these creatures still realized that a hive would provide them with all they needed.
An Enslaver usually begins by sneaking into an existing hive, masked by his pheromones, and steals a few eggs. Some will be used directly as nourishment, as they are saturated with love, and some will be kept for later use. As the changelings in the eggs grow, the Enslaver showers them with pheromones to put them under mind control. When they eventually hatch, he sends them out in his stead to collect love. The Enslavers have adapted so well to this lifestyle that they've lost their ability to transform and fly. Their horns and wings have atrophied, instead giving way to pheromone glands all over their body. They stand a bit taller than the average changeling and don't seem to have any offensive weapons left, instead often running away and abandoning their "hives" as soon as they are found out. The changelings they've enslaved wither and die as their bodies cannot survive without the pheromones from the Enslaver.
Although an Enslaver's pheromones are amongst the most powerful found - they can be used to confuse and incapacitate other changelings - a queen is still able to "sniff them out", so they have to be very careful whenever they get new eggs. They don't mind the risk much, since their consequent enslaving allows them to live a life of luxury and laziness. In a cruel mockery of the original hive, they are the self-styled kings of their little "family".
Or pheromone's change that ?
But I was wondering: How do they reproduce? One of the previous comments you replied to states that Enslaved changelings can turn into them due to constant pheromone showering, but there has to be more than that if they're really a separate subspecies. They are obviously solitary, since a hive of slavers would draw the changelings' attention and they'd all get in each others' way. But, are there any "queen"-type slavers, which somehow reproduce more slavers? Or do they make like a virus: injecting their genetic material into a changeling egg so that it hatches into a slaver instead? I'd be interested!
otherwise i was thinking that if an enslaver is killed (most likely inside a hive), his dying body releases a shower of pheromones that infect any changelings nearby. i'm not sure if there's a treatment, but if one changeling who's been hit goes long enough unchecked, he eventually turns into an enslaver too.
so its like my hive
I can't see a Chrysalis-born Enslaver meeting with much success in trying to steal any of Miasma's eggs unless they do it very quickly or unless all Enslavers lose all their hive-specific markings.