James Gasik
We don't talk about Pun-Pun
If your definition of "overpowered" is merely the benefits the Deck can bring (and we won't discuss methods of abusing the Deck, like casting Augury before each draw and the like), sure.I wouldn't say a deck is overpowered. Potentially campaign disruptive, sure, but not really in an overpowered way when averaged out.
But I find the character ending downsides that offer no saving throw to be pretty overpowered in their own right. Donjon and the Void for example. The Flames and Death, at least, give you a fighting chance. And then there's Ruin- which is so ambiguously worded that it apparently has the same function as Talons.
Like any cursed item, if the players find a way to weaponize it (see Dust of Sneezing and Choking, the Necklace of Strangulation, the Cloak of Poisonousness, the Scarab of Death), by deceit or mental manipulation, it can wreck campaigns in completely unintended ways unless the DM starts adding rules to it.