Monsters and NPCs
The referee is responsible for deciding how monsters and NPCs react when encountered, but also what schemes and tactics they follow when the PCs are elsewhere.
Intelligence and Tactics
When deciding how a monster or NPC acts, the referee should bear its level of intelligence in mind. Intelligent monsters might use any of the following tactics.
Traps and stealth: Monsters which are cunning but not physically powerful might lay traps or ambushes and may favour attacking PCs from a distance with missile weapons.
Guards: Monsters may make use of guards or pets to weaken PCs or to protect important escape routes.
Magic items: Monsters will use any magic items in their lair to thwart the PCs.
Learning and preparation: If PCs encounter but do not defeat monsters, the monsters will learn from the experience and prepare for a repeat attack. They may build defensive structures, call for reinforcements, relocate their base of operations, and so on.
Adaptation: Monsters may copy or adapt tactics successfully used by PCs and may plan specific counter-manoeuvres.
When designing encounters, the referee should bear in mind that—like player characters—monsters and NPCs will join forces in order to increase their chance of survival.
Combined forces: Monsters skilled in melee, missile attacks, and magic may join forces.
Leaders: May have special abilities, maximum hit points, or additional Hit Dice.
The same as player characters, intelligent monsters and NPCs have their own interests and motivations.
Role-playing: The referee should consider the monster’s reaction to negotiations with PCs, bearing in mind its alignment and personality. Monsters should not always cooperate with PCs’ wishes!
Allies: Monsters and NPCs may be encountered with friends, minions, or retainers. These will come to the aid of the monster, or may avenge it, if it is defeated.