Psychic
Can visit a player at night. That player's night action will be overridden by the mod, who will use it/direct it in the most beneficial way possible (for the targeted player) for that night.
I.e. if the psychic visits a doctor, that doctor will automatically protect that night's scumkill. If the psychic visits a cop, they will target scum (usually, or perhaps a scummy town player). If however the psychic visits scum, the action will be in the scum's best interest (i.e. kill the most powerful PR, etc.) even if the psychic is town-aligned. These aren't fixed rules though; simply put the mod has to direct/use the action in the best possible way given full knowledge of the setup, current situation and everyone else's night actions for that night.
Fortune Teller
Can visit a player at night. That player will receive a 'fortune'. This consists of a statement regarding a certain action that will occur to them in the future.
For example it could say "You will die on the next night", or "You will die the night after the next", or "You will be visited by someone special on the next night" (this can be specific or vague).
The content of the fortune will be at the mod's discretion, or can be somehow randomised.
Then, on the night of the fortune, if it is possible for the action to occur, then it will occur, by switching around the night actions however necessary (i.e. redirecting a NK onto the player, etc.)
I would definitely notify a cop if their action was redirected. As for other roles, not sure.