[Aleph]

Claws/Prison always work - at least, I've never seen them fail. And if you can't beat them, join them - come over to Blood.

I've been trying to enslave horrors with Hellbind Heart, and it doesn't work - the battle ends when the spell goes off successfully, but you don't get to keep the horror. I think it's more about the assassination format, though - I've definitely gone for the Dreams of Rl'yeh / Enslave Mind combination in the past, and the same result - you're considered the victor, but you don't get the commander.

BUT I too have been having a great time in a LA Mictlan game with Astral Corruption - I beelined straight to it after a slight diversion for SDRs and Jaguar Toads. Then I finished out Blood Magic so I could have access to Claws of Cocytus and Infernal Prison. These work 100% of the time on horrors, just like they do everything else (at least, I've never seen them fail, and that includes on Kurgi and several other Doom Horrors). Trouble/opportunity is, horrors are tough - especially the kind of horrors (like, say, Kurgi) who show up looking for trouble when you have cast a 100+ gem global spell under Astral Corruption. So they eventually find their way out of Inferno, and once they do they are regular units in the world. So at that point you've got a shot at enslaving them.

I haven't pulled it off yet - one time I brought too large an army and my commander decided that it would be a waste of resources to hellbind a horror, and fighting Kurgi my placement was off and my commander didn't advance into hellbinding range. But I'm convinced it's possible, and I think blood magic is the way to do it - it's the lowest level domination spell in the game in terms of path requirements, therefore you can get the highest amount of bonuses for going above and beyond, and bloodslaves are accessible in much larger numbers than other gem types. They also make a nice human shield around your spellcaster.

I haven't yet gotten to the point of casting Send Horror at my own army, but I'm getting there. Since that's a battle format, not assassination, and yet the horrors normally go away at the end, I'm not sure what the net result will be.