Hypnosis

You have the ability to make your victims enter a highly suggestive trance during which you can alter their mind and behaviour in any way and for whatever amount of time you please. You should be careful though, even if it hasn't happened yet, there might very well be people that are hard or even impossible to hypnotise (especially in the bigger and more powerful guilds, you assume). Furthermore you should be cautious about how much attention you'll want draw to yourself as being too suspicious or overconfident might have you end up either dead or rotting in a cell.