I'm going to run the D&D adventure White Plume Mountain, and I want to replace one of the puzzles with a good riddle.
Here's what I've got so far:
The mage with the mansion:
There is a D&D spell "Mordenkainen's magnificent mansion"
The sorcerer who did surgery:
Strange (Found by Alexander Geldhof)
Dr. Strange, doctor = surgery
The bro with the fist bumps
There are several fist-related D&D spells such as "Bigby's clenched fist" and "Bigby's crushing hand"
The guide who was the gray
Gandalf the gray, who guided Bilbo and Frodo
The one with the orbs
There are several D&D spells that are orb-related such as "Otiluke's Freezing Sphere" and "Otiluke's Resilient Sphere"
The villain who talked to vipers
Voldemort (found by Alexander Geldhof)
From Harry Potter, who famously could talk to snakes
The channeler with the conflagration
From Magic the Gathering, where there are several fire-related cards, such as "Chandra, Pyromancer" and "Chandra, Acolyte of Flame"
The enchantress who was endothermic
From Frozen the movie, who had ice powers
And the greatest wizard of them all
From D&D's White Plume Mountain adventure module, where this riddle is set (from the title).
If you take the letters in the numbered blanks 1..11 from the previous answers, and fill in the given blanks _____ ______, you get:
If you take the original version with the scrabble tiles, and remove the names of the 9 wizards, you get these letters:
Which anagrams to TILES.
Maybe this is obvious, but my guess at the method of the puzzle is that we are supposed to decypher the cryptic clues and then scrap them from the letters. I suppose 'The villain who talked to vipers' is Voldemort, 'the sorceror who did surgery' is (Dr./Doctor) Strange. Note that those both alliterate with the cryptic clues they correspond to.