Slagg is a graduate of the Vancouver Playhouse Acting School whose early career was primarily in theatre. He has since moved more into the realms of film and television. He subscribes very much to the Guskin school of acting outlined in Harold Guskin's seminal work, How to Stop Acting. This forms a foundation not only of his technique as an actor, but of his coaching and theatre directing as well.Slagg notes, "Actors know how to walk about and say lines to each other, that is trivial; the work is to discover the essence in the action, the heart in the words."Where Slagg differs from Guskin is in that he believes that intuition, essential to a living performance, is educable, and so it is worthwhile to engage in study of the script, intentions, beats, physicality, etc. Come the day the actor forgets all that, confident that nothing can be forgotten. Intuition has access to all.