A Brain Push is a skill of Telekinesis only ever known to be performed by the Ancients and Sophie Foster. Brain pushes use mental energy instead of core energy, which is quite difficult. Sophie uses brain pushes throughout the books, such as during Fintan's healing. Her brain push in the first book slammed both Fitz and her into the walls during a Splotching match. This was because mental energy (used by Sophie) and core energy (used by Fitz) don't mix, and instead rebound when they come into contact with each other. Before Sophie, only Ancients were known to perform such an incredible feat.