You have followed in the Chosen of the Dead Three’s footsteps.
You have gained control over an elder brain—no easy feat. With your control, you can force the brain to spawn more tadpoles. Through the Netherestones, the Elder Brain has evolved past its previous limitations, holding a vast psychic might that puts it above normal Elder Brains. Furthermore, the elder brain no longer has a limit to the range in which it can control those affected by ceremorphosis.
Perhaps through this evolution, the Netherbrain has regained the knowledge that the Ilithid Empire once had, as within it holds a lost understanding of technology that the Ilithid Empire once used to conquer the galaxy.
By magically examining the crown, you have removed the weakness of the Netherstones and instead turned it into an advantage. So long as the crow retains the Netherestones, you have gained a fraction of the divine power the Dead Three lent to their chosen.
Through the stone that Kethric once wielded, you have gained insight into the domain of death and, in time, become capable of seizing the domain, in addition to the ability to be invulnerable to damage for as long as the elder brain still lives.
Through the stone that Orin wields, you gain insight into the domain of murder as well as the ability to kill that which cannot be killed.
Through the Netherstone that Gortash once employed, you have gained insight into the domain of tyranny and the ability to control the minds of others to a greater degree, even those with immunity.