"Difficulty" may be any one of the following arguments: 1, 2
1 5 players normal 2 5 players heroic
When the change occurs a message will be shown in your default chat.
When you use this function the saved instances will no more be reset.
There are two more parameters to the function, but it is not currently known what they do.
/script SetDungeonDifficulty(1); /script SetDungeonDifficulty(2);
"Dungeon difficulty set to 5 player" will be shown in your default chat. Then "Dungeon difficulty set to 5 player (Heroic)" will be shown in your default chat.
3.2.0: 3 (epic) removed and added a new function API_SetRaidDifficulty for the new split between normal/heroic and 10/25