Item Decent - Princess Peach

((Porting this idea from my thread/path over on babytoast's Bad Ends. I'm unsure as to how much corruption/transformation they would allow, so better have that focus here))

The Mario Universe is well known for all manners of items that transform or alter a user. From Mushrooms, to magic, to raccoon tails to super capes; the possibilities are endless.

But there's so many items lurking in the world, it's almost impossible to say for sure the effects of them all. Or worse, what happens should you mix them. Not to mention the goals of those that might have sent it.

So when Princess Peach, eyes wide about what could be in the present sent and addressed to her, opens it in her private chambers, what could contained inside?