Mina's Talisman is an accessory from Castlevania: Dawn of Sorrow. It is enclosed in a letter addressed to Soma Cruz by his childhood friend (and possible love interest) Mina Hakuba, and has no effect whatsoever on Soma's stats or abilities. It only comes into play at the end of the game. Celia Fortner attempts to bring forth the darkness in Soma's soul and create a new Dark Lord by murdering a helpless Mina right in front of him. If the Talisman is not equipped, Soma gives in to his rage and despair, and embraces the evil within him, in the same manner that Mathias Cronqvist did hundreds of years earlier when he became Dracula. However, if Soma is wearing Mina's Talisman, he will hold off the darkness just long enough for Genya Arikado to arrive and reveal that Celia's show is a lie: Mina is still safe at home, and the creature killed before Soma's eyes is a Doppelganger. This revelation allows Soma to regain control of himself and prevent the darkness from taking over, letting him continue the fight against evil.
It is possible that Mina's Talisman is made to do the opposite of the Crimson Stone as it resists dark power and influences rather than absorb it.