Morale checks are used to determine the amount of will to fight in non-leader NPCs, and can be applied both to henchmen and hirelings of character types and groups of intelligent opponent monsters.
The base unmodified morale score is 50%. [Creatures that roll this number or LESS succeed the morale check.]
Other modifiers to a Morale Check roll:
Bonuses
Penalties
Henchmen or Associated Creatures. For each creature take the base morale (loyalty) score and cast percentile dice. Adjust the score for penalties and bonuses, and if the adjusted score is equal to or less than the loyalty score, morale is good. If the number exceeds the loyalty score, the creature will react according to the morale failure table below. (See Non-Player Characters, Loyalty, Obedience, and Morale.)
Monsters, Intelligent. Each monster has a base morale of 50%, +5% per hit die above 1 HD, +1% per hit point above any hit dice. e.g. A troll with 6+6 HD would have a normal morale score of 81%.
If a morale check is required, scoring and reaction are as stated above for henchmen et al.
The difference between the maximum score needed to retain morale and the number actually rolled, as adjusted, is the % of morale failure.
N.B. Certain fanatical creatures and some non- intelligent creatures do not normally make morale checks. Additionally, special circumstances will obviate (the need for) a morale check. These will be noted in the creature entry in the Monster Manual or the encounter text.