I'll go pretty straight, but you probablya all know many scenes were cut from The Black Cauldron by the producers to avoid a too adult rating of it in theatres. The nature of the scenes, however, is mostly unknown, except for this unfortunate scene where one of the Horned King's living soldiers was dissolved' to death by the ghosts. Well, I think there is a bit of the Horned King's death that has been deleted. Let's rewatch the scene: it is on Youtube here

Did you watch it ? Good. Did you notice anything ? Perhaps not ? In that case, rewatch from 01:43 to 01:56. First we have Eilonwy and Fflewdur arrive in the Cauldron's room, and Eilonwy says "oh, no". The next frame shows us why: she sees Taran lying on the ground near the Cauldron why the Horned King is about to escape. Then we have a short shot of Taran awaking and starting to move toward the direction taken by the Horned King. And then… we cut to the Horned King beig dragged to the Cauldron. Wait ! Wait ! Wasn't he successfully resisting the sucking force a few seconds before ? What made him looses his equilibrium ? And what with Taran moving toward him of a few centimers just before ?

I think there was a shot where Taran would crawl to the Horned King, and catch his ankle or something to make him lose his equilibrium. That would make more sense.

And it also makes sense that the producer would have cut such a scene (the hero actively murdering the villain, even if the villain is a horned lich with red glowing eyes, was not something they could have got away with if they wanted a children rating). 

What do you think ?