How and why does Vecna's curse transform wizards into Nothics?

Question

The description for the Nothic in the 5e Monster Manual contains the following text:

Rather than gaining the godlike supremacy they crave, some wizards who devote their lives to unearthing arcane secrets are reduced to creeping, tormented monsters by a dark curse left behind by Vecna, a powerful lich who, in some worlds, has transcended his undead existence to become a god of secrets. Nothics retain no awareness of their former selves, skulking amid the shadows and haunting places rich in magical knowledge, drawn by memories and impulses they can't quite understand.

Is there any further detail elsewhere? Is this something that just happens? Could a wizard (or other spellcaster) in my game just wake up one morning a Nothic for no reason? Or are there other variables involved?

If it helps to answer the question, what is Vecna's curse? Are there any related publications that entail it?

Answer 1

Your party wizard is safe, probably. A wizard in your game might wake up one morning as a Nothic. It's not for no reason though, it's because of Vecna's dark curse. They were most likely trying to uncover some dark secret, and got in over their head. Ultimately though, your game may not even have a deity named Vecna, so it's up to you to decide what a Nothic really is.

The answer to "what is Vecna's curse" is entirely DM dependent. The entries in the monster manual aren't necessarily intended to form a complete world, but to provide enough inspiration to the DM to be able to incorporate the monster into their own world. Vecna is a powerful lich or deity who has a dark curse that turns wizards into nothics. The mechanics of how this happens, or what the curse might be, are left open to the DM to elaborate on if it is important to the campaign.

Answer 2

There are no mechanics in DMG or MM that speak to how it happens. As such it is something that "just happens" in that it's completely at the GM's whim to how it happens.