Mechanics (2)

Understand AD&D rules like Armor Class, THAC0, and Saving Throws in Shadows of Doubt. Learn about magic and weapon speed.

Armor Class (AC): This measures how difficult you are to hit in combat. It starts at 10 and decreases, with more negative numbers being better. A bonus to AC lowers the number.

THAC0 (To Hit Armor Class 0): This is a measure of your probability to hit an opponent with a twenty-sided die (d20). At ninth level as a Fighter or thirteenth level as a Cleric, your THAC0 is 12. This means you hit on a roll of 12 or higher before armor modifiers. An opponent with AC -2 requires a roll of 14 or greater (14 - 2 = 12), while an opponent with AC 1 requires a roll of 11 or greater (11 + 1 = 12).

Saving Throws: The same d20 roll used for attacks is used for saving throws against magic. You must roll greater than or equal to your saving throw value to succeed. For example, a saving throw of 16 vs. spells gives you a 1-in-4 chance to avoid harmful magical effects or reduce damage. Saving throws decrease as you gain levels. Different saving throw values exist for different attack types.

Magic System: Unlike games with a mana pool, magic in Shadows of Doubt uses a finite number of spells. Once cast, a spell is gone until you rest. Mages can only cast spells they know, acquired by buying or finding scrolls and writing them into a spellbook.

Weapon Speed: This is a number between 0 and 10, where lower is better, determining attack order. Magic casting time is equivalent to weapon speed. If you are hit during casting, the spell is interrupted. Weapon speed is unrelated to your attack rate.

Attack Rate: This depends on Fighter level and weapon skill. You start with one attack per combat round. Reaching two weapon proficiency points or level 7 Fighter level grants an extra half attack per round. Level 2 proficiency and level 7 Fighter levels grant two attacks per round. The maximum attack rate is 3, requiring level 5 weapon proficiency and level 13 Fighter levels. This applies to melee weapons; missile weapons have different base attack rates.

Levels: The term 'level' can refer to a dungeon section, a character's power and magic capability, or general power (e.g., 'high-level loot').

Experience Points (XP): Characters gain levels by earning XP from defeating enemies and completing quests. The XP required for each level increases exponentially. After certain levels (9 for warriors/divine spellcasters, 11 for Mages/Rogues), subsequent level increases require a fixed amount of XP, ranging from 220,000 for Thieves/Bards to 375,000 for Mages/Sorcerers. XP is divided among party members.

Hit Points (HP): HP measures your and your enemies' vigor. You see your HP, but enemy health is indicated by states like Uninjured, Injured, Near Death. If your HP reaches 0, you die. Companions can be revived at a temple or with a spell. On Core Rules difficulty and higher, taking damage that results in deep negative HP causes permanent death (a reload condition). On Story Mode, characters cannot die. On other difficulties, manage HP with healing magic or by resting.

Weapon Proficiency: To hit effectively, you must spend at least one proficiency point in a weapon. Not being proficient incurs a THAC0 penalty from 2 (warriors) to 5 (mages). Only single-classed Fighters can exceed proficiency level 2 in most weapons.