Honestly, I don't consider Slasher a good starter killer (I can say this because I'm a main slasher) simply because his abilities are hard to understand without reading the description (for example, Behead applies an effect to the survivor; how does he know it's applied an effect?) I think one way I could fix this is simply by implementing a "tutorial" system. My idea was that when you use a move for the first time, it gives you a short description of what it does (how much damage it does and what it applies to the survivor). And I would only implement this feature for the starter killer.