I'm sorry, I never used it. But what I have read about it, is that it is a skill like the beastlord "tame" than can be used on trained units, this is, units that AI has trained in a city. It is not valid for beasts, monsters, champions, summons, etc. Only trained units. No need to say a Garrotte is not a trained unit...

Is it worthy? I think not, as I don't see AI deploying powerfull units, but some people find it interesting...

Maybe if you find a yithril juggernaut, you could try to "tongue" it (but again, not on an scaped juggernaut, I guess that is not considered a "trained unit").

Trained units would be soldiers for the most part.  I use it all the time to take a unit of mages, archers, horsemen, from the enemy AI during combat.  It doesn't work on Jugs, as far as I know.  "Trained' usually refers to things that a city can produce, but I know it doesn't work on Jugs, and I doubt it works on henchmen or Golems.  Kind of funny that "Diplomat" gives you an ability that only works when you are at war, not peace.

But, I had no idea it worked on Syndicate, that's interesting...

Does it work on garrison militia/archers? Never tried, but have wondered ...

That's make no sence as well, spider can't be reason and bride to...I guess it's only work on common solder who can be bride, but not a monster who don't care about a gold or men but repect to one who training them this way...unless you beastmaster..