According to Chris Perkins in a very recent interview on Waterdeep:Dragon Heist, he said that there are "almost" 200 Noble hoses in Waterdeep. I would consider the main author of Waterdeep: Dragon Heist claim of "Almost 200 to be a source for canon. You can easily find that interview on YouTube.
Yep, they definitely can
Looking at the 3rd Edition Forgotten Realms Sourcebook Faiths and Pantheons, we get this as a listed Salient Ability that a god may have (i.e. a "things a god may be able to do because they are a god")
The deity can cast spells whose effective level is above 9th. The number of spells per day the deity ...
According to the AD&D book, Secrets of the Magister, it is still possible for mortals to research and cast 10th level spells
In the Forbidden Magic section of the Magisterial Magic chapter of the AD&D book * Secrets of the Magister* (published in 2000):
After the Folly of Karsus [...] , the newly ascended Mystra stripped mortals of the ability to ...
I cannot speak for Berdusk, however Elturel is prominently featured in the Descent into Avernus,
A plane shift spell transports ****** the wizard and up to eight other creatures to Elturel
So at that time magic obviously isn't protecting it from teleportation. However, if you are aware of the plot, things have happened in the town.
It's worth noting that ...
In the Appendix of Hoard of the Dragon Queen, it gives the following information about the Red Wizards.
Red Wizards of Thay
Red Wizards are the would-be magical overlords of Faerûn.
Feared by the general public as evil tyrants, Red Wizards trade their magical inventions for slaves, steel, silk, and gold.
As magical artificers of great skill, ...
Yes, but with story-continuity caveats
The lore regarding Tiamat is varied, it has been interpreted and reinterpreted many times throughout the editions and campaign settings. In 4e and 5e, Tiamat and Takhisis have been confirmed to be the same entity, so the lore also includes many Dragonlance stories. Here are two actual examples of Tiamat/Takhisis being ...
Once a humanoid has fully transformed into a mind flayer, the original humanoid is dead and their body is destroyed.
In the AD&D 2e sourcbeook Monstrous Arcana: The Illithiad, p.11, asserts that most normal means are ineffective at restoring their original form:
Ceremorphosis completely replaces the original tissue of the victim with illithid tissue; ...