Radagon’s Icon talisman adds 30 additional Dexterity to your spell casting. If you have 20 Dexterity towards spellcasting, it will be bumped to 50, reducing the time to cast spells by a huge margin.

In order to reach this talisman, you'll need to have reached the Debate Parlor Site of Grace. Radagon Icon talisman location From the grace, head toward the large gates and into the courtyard.