Diplomacy is a secondary skill, that increases the chance wandering creatures will offer to join the hero's army and lowers the cost of surrendering to another hero. Additionally, Diplomacy enables hero to learn primary skills from Library of Enlightenment earlier than experience level 10. With Basic Diplomacy hero has to be at least on level 8, with Advanced Diplomacy on level 6 and with Expert Diplomacy on level 4 to receive +2 to all primary skills from Library of Enlightenment.
Heroes with Diplomacy as a starting skill:
Basis of joining
Whether or not the wandering monsters will join you for "greater glory" or at price, depends not only on a hero's level of Diplomacy, but also on several other factors (see also External Links below).
First, the primary skills of a hero and the strength of the army that this hero leads are combined and then compared with the strength of the wandering monsters. The greater the relative strength of the hero’s army, the more likely it is that the monsters will join.
Second, the chance that wandering monsters join is increased when the hero’s army contains at least one upgraded or non-upgraded creature of the same type as the wandering monsters. The chance of joining is further increased when more than half of the creatures in a hero’s army are of the same type as the wandering monsters. Note that fire and energy elementals, water and ice elementals, and earth and magma elementals are considered different creature types, even though the latter of each pair is an upgrade of the former.
Third, when playing at easy difficulty, heroes receive a diplomacy bonus, even when they have not learned the skill. This does not affect heroes with expert diplomacy, but no Diplomacy acts as Basic Diplomacy, basic diplomacy acts as advanced diplomacy and advanced diplomacy as expert diplomacy.
Fourth, these three factors together are compared to the aggressiveness of the wandering monsters. A group of wandering monsters that the mapmaker has set to ‘compliant’ will always join, whereas a group of ‘savage’ wandering monsters will never join. The default setting is ‘aggressive’, meaning that at the beginning of the game the aggressiveness of each group of wandering monsters is pseudo-randomly determined to range from as high as those of ‘savage’ monsters, to so low that creatures may join even when neither diplomacy, nor any creatures of the same type are present. ‘Hostile’ monsters have a higher aggressiveness than ‘aggressive’ monsters but might still join, whereas ‘friendly’ monsters have a lower aggressiveness than ‘aggressive’ monsters but still often fight or flee.
Diplomacy reduces the cost of surrendering, and increases the chance of wandering monsters joining you, be it 'for greater glory' or at a price.
Recommended for: At least one hero, typically a support, on maps with wandering monsters that are not set to 'savage', but preferably to 'aggressive' (i.e., the default setting).
Although a main hero's attack and defense skill help in convincing wandering monsters to join, it typically works well to let a support hero learn this skill instead. This support hero can then borrow troops from your main hero to convince wandering monsters to join and return the troops immediately after. This saves your main hero a skill slot and potentially a lot of movement points.
- Diplomacy internals - thread on HeroesCommunity
- Tribute to strategists: Heroes of Might and Magic III Manual by Rainalkar, pp. 22-25.