Other posts say enslavers 1st appear at floor 20. Here’s some legend pet tips as well.
I personally hunt them on 183-185 because I like that map type for finding them. Takes me 20-30 secs avg. Apparently Max luck is what makes the difference. I run floor 185 M3 with 850 luck & 700% eternalized and don’t see many random eternal drops. I just run 185 M3 until I reach 149 kills then complete the feat on 500 for Merlin chance.