So, my friends and I were playing and they picked up the Hypnotism card fairly early in the game (I had no vampires at the time), and considering that Mina Harker is always bitten there is not much of a chance that this card will not be used.
We were considering that if Dracula has 1 or 2 vampires, another Hunter has to be in the same location for this to work. However, if Dracula has 3 or more, then it can be used at any time. We haven't come across it again since, but was wondering what everyone thought of this amendment to allow a bit of fairness if Dracula has barely started allowing his dark plans to come to fruition.