Ir

Ir was a mind flayer psionicist who lived in a chasm near the Darklake in the Underdark. It was unknown if Ir was a real person or a fictional character. They featured as one of the characters of The Daring Duergar, one of the tales of Fables of Faerûn.

"So be it. It is yours - the knowledge to shatter a single mind. But you may only speak the command once, for them it is forever forgotten."

- Ir the mind flayer.

History
At some point, Ir was approached by a young duergar from Gracklstugh named Shull, who wanted to hone their psionic powers. Ir taught Shull how to read minds, and even control, them but the duergar was not content. Shurr wished for the ability to destroy minds outright.

Ir blessed Shull with the ability to destroy a one mind on one single occasion. Once the power was used it would then be lost to him for all time. Unbeknownst to the young duergar, this power would in fact shatter the user's skull, rather than the mind of whomever they targeted.