So the Enslave is a very interesting change, that is both stronger and weaker than the vanilla version.
- DC 16 vs 14 (thank god, I've used aboleths in core and that 14 DC is weak sauce)
- 60 ft range vs 30 ft
- Requires Sea Change Disease vs any target (this is a big one, vanilla Aboleths would often open with enslave, in LU you have to work for it, that's a major nerf).
- Legendary Action vs Regular Action
- Full functionality vs Loss of Reactions
- Save every 24 hours vs No save if remains within 1 mile of Aboleth
- Can go anywhere vs Must remain on same plane for the effect to remain.
However, things get interesting when you consider an Aboleth attack as part of a strategy. The aboleth gets off the disease and leaves. Well now your diseased character is extremely vulnerable to follow up aboleth enslave, and that disease is likely to linger. Considering an LU aboleth can generate 3 charm saves a round on a single character....its highly likely you will fail. It gives some strong incentive to address the disease immediately as opposed to waiting until the underwater part of the adventure is over.
I'll echo others that the Legendary Resistance concept is very cool. I have been very disappointed with the vanilla aboleth (I've used them twice in games and they were comically defeated both times)....in terms of a total package this aboleth looks a lot better.
