I'm not sure how or if HM is going to have this sort of thing in the rules, so I'm writing up my quick rules. When the adventurers encounter some intelligent monsters in the dungeon (or other less awesome adventuring situations.) and they do something other than immediately attack, time to grab the dice and drop a reaction roll ... but what to roll? And what modifiers?
First up, only roll for intelligent monsters. Second, the roll indicates what the monsters are up to, not what they do. For example, a roll of "Distrustful" might end up in getting ambushed later on whereas "Cautious" might mean the monsters try and hide. Anyway, make an initial roll, then roll again after attempts to parley and whatnot. I'm leaving it pretty open-ended rather than formulaic.
The Classic Reaction Roll
In BX Holmes the reaction roll was a simple 2d6 modified "if the party spokesman has a high charisma or offers special inducements." Nice and straight forward, but about half the time(or more) dungeon monsters would be friendly.
BCEMI Menzter added some cascading rolls (up to two more rolls) adding more granularity, but with added complexity ... or at least taking more time. The rules also mentioned actions by the players for some mods. The final values were approximately:
...which is still a bit on the nice side as far as I'm concerned. In either situation, a party with at least a little charisma is going to end up with neutral or friendly monsters. This doesn't mean they are pals, but that they can wander by without trouble.
The HMAEE Reaction Roll
The Level of Danger determines the reaction roll dice. LoD is probably the same as the dungeon level - in cases of wilderness or city the GM should know about how dangerous a place is. The lower you go, the more dangerous it gets. Of course, once the PCs start making a name for themselves by killing the locals, add 1 for each intelligent monster battle they STARTED. Berzerks attacking the PCs doesn't affect how the goblins think of them. If the party wants to be murder hobos, then let it commence.
|PC actions when they attempt a parley have a huge impact. Good moves reduce the roll by -1 to -5 (depending on the skill of the PC) and idiot things make life tougher (+1 to +5).|
Offers of food, bribes, information, alliances, as well as judicious uses of fast talking, diplomacy, and similar skills can get those bonuses.
Of course, for a parley to work both parties have to speak the same language, which can be a challenge and requires a skill roll (from one side or the other or both). Failed skill rolls mean a lack of understanding where a catastrophic skill roll means a misunderstanding. "I think you just told that bugbear you nailed his sister behind the Bishops Arse!"