"Blood Omen 2" and "Defiance" include experience point systems, and in the "Soul Reaver" games and "Defiance", the player must shift between the material and spectral planes of existence to progress – both realms have unique physical laws, geometry and enemies. The Soul Reaver sword, a recurring ultimate weapon and soul-devouring blade inhabited by a ravenous entity, appears in all five titles. Dialogue in the series is florid and Elizabethan in style, inspired by period pieces such as "Becket", "The Lion in Winter" and "A Man for All Seasons", and each game was scripted in the manner of a stage play, with monologues, asides and cutscenes interspersing gameplay. During "Blood Omen"'s production, Silicon Knights hired classically trained actors to deliver voice talent, a precedent which Crystal Dynamics continued in successive games.