glamour
(Anonymous)
"transfigured himself into a couch pretty well."
Given what Dumbledore says in Beedle about self-transfiguration into an animal (one loses one's human mind and can't transfigure back) it seems unlikely to me that Slughorn had used transfiguration. There's no other canon evidence for that very popular fanon device of glamouring, but I do wonder if the armchair thing was an illusion rather than a transfiguration.
duj
Given what Dumbledore says in Beedle about self-transfiguration into an animal (one loses one's human mind and can't transfigure back) it seems unlikely to me that Slughorn had used transfiguration. There's no other canon evidence for that very popular fanon device of glamouring, but I do wonder if the armchair thing was an illusion rather than a transfiguration.
duj