D&D General The Purple Dragon Knights are tied to an Amethyst Dragon (confirmed)

[I'm A Banana]

Because if a character reaches the natural end of their narrative and that end is death then undoing it is bad.

So much depends on the context and execution.

Like, the "good" ending of FFX-2 was pretty well done, but so much of both that game and the one before it were about dealing with grief and loss that it felt kind of cheap, like a forced happy ending.

And, "Somehow, Palpatine returned" is a meme for a reason (the reason being that it's dropped like a brick into the storyline and is clearly more about "Hey, I recognize that reference!" brand appeal than about the needs of the story).

But, like, Sauron returning to Middle-Earth and being a threat again was a pretty cool idea. And I like that part of Zargon's myth-making is that he is "the Returner," he is just not a creature that can be defeated easily. And, D&D has enough comic book shenanigans in it that coming back isn't a HUGE curve ball (maybe he's a CLONE!).

It might really cheapen the original storyline if he's back in a silly or unearned kind of way, but I think there's a bunch of paths I'd be OK with, especially if it means I get to have an adventure where I smack around Sammaster and some dracoliches or something.

 

[Sorcerers Apprentice]

The main thing I dislike about iconic villains coming back from the dead no matter what is that it reduces the satisfaction of defeating them. No matter how much the PCs hate Sammaster and want to destroy him, if they are paying attention to the lore they know any victory is just temporary.

For some villains that's OK, like a central element of Strahd's and Ravenloft lore is that the darklords always return. But if every villain in every setting can come back just by being cool enough, it starts to feel really cheap and contrived.