I actually quite like the idea that even when Aman'thul annihilated Y'Shaarj, he ends up going over to the Shadowlands and, because of how badly he was killed, was only a small corrupting force but slowly begins working whatever he could to play the long game from the other side.
Y'sharaj was also still active despite just being a Heart with barely a beat & while Garry basically fed that heart some water to make it empowered again and then ate that heart until nothing was left its still pretty apparent he had a lot of power still. With the sha and such.
