I used the Deck of Many things in my Curse of Strahd campaign. Strahd himself gifted the party the deck as a way to torment them. Most of the results were changed slightly in order to better conform with the theme and plot of the adventure.
For the Rogue, the enmity is always borne by Van Richten.
The Throne grants rightful ownership of Argynvostholdt.
The Void sucks the PC's soul into the crystal heart within Castle Ravenloft, with its destruction freeing the PC.
The Talons deposits all of that character's items into the Castle Ravenloft treasury.
Donjon whisks the PC into the dungeons underneath Castle Ravenloft.
Since my campaign uses milestone experience, any card that granted a set number of experience points instead granted one flat level.
Its use did have a large impact on the campaign. One of the players had three good draws, including one that granted him a Staff of Ice from a wish. Another player drew the Donjon and was entombed while holding the Sunblade; he used the opportunity to secretly become villain for a dramatic party betrayal before rolling a new character. A third player drew the Void, though he moved out of town shortly thereafter, so it did not significantly impact the game. Otherwise, the party would have the option of a focused raid on the castle in order to run in, smash the heart, and run out.
Of course, the Chaotic Neutral fighter drew the worst card of all: the one that made her character Lawful Good.
