I tried my best, but didn't get even close to getting the ghost knight. And I have been slaying knights vigorously. Voodoo knight drops were not too good either. I expected the ghost werepea and mummy fangpup to drop treat bags as well, but unfortunately they didn't. Gave up on the bone dire boar, because I was getting just about everything, but paint and brushes.
Didn't upgrade the tomb past level 3, because I had to choose, and new skins would have been nice, but aren't necessary. I did get quite a few withered roses which seem useful after the event because they drop red and white petals now. A source of red petals is always welcome for a lot of players.