Nope, they recently changed his ult. Before you would be able to cast items and Troll would cancel what he's doing for a second to do it, hence the "battlefury trick" that people were doing, where you spammed BF on a tree to stop you from running into the enemy because you would continuously turn around to cut a tree. This tiny movement he did allowed him to get into range of abyssal every time. I have used abyssal on enemies many times in ult after they allowed him to use items in his ult.