first of: I am sorry, but I own the German version of the game, and I have not found kind of a detailed list about all the different cards and items in game. Therefore I try to describe my issues with "The Guitar" and "Melee Combat". I hope you will be able to help me out regardless of that ...
Today three friends and I played the fourth scenario of Mansions of Madness with the main clue 1c. Therefore the three investigators hat to kill the Witch Detaigne.
During the game I as the Keeper used an action against one of the investigators - the one controlling him and using one of his items against another gamer.
Question one: The friend of mine played "Ashcan" Pete, and he had his guitar. The description for the guitar says something like this:
Action - discard the guitar and attack a monster.
May I as the Keeper use this against another Investigator although Investigators are not monsters?
Question two: So I did - I used the action for the guitar of "Ashcan's" with "uncontrollable urge" (or something) against another Investigator in the same field. And I drew a melee combat card, which reads something like this:
Check your strength. Success: He aches and is convulsed in pain. You deal Weapon Damage + 1, No Success: He grips your weapon and pulls it off your hand. You drop the Weapon.
When we played along the card, "Ashcan" had no success with his by me controlled attack; so according to the Melee Attack card the Guitar should have been dropped to the ground of the room; bot otherwise the guitar description says that you discard the guitar card as soon as you take an action to attack a monster with the guitar ... So would the guitar remain in game but dropped to the floor, or would the guitar be discarded?
Besides all this: His there somewhere a list of all the cards of the game available on the internet?
All the best!