Advanced Dungeons & Dragons 2nd Edition
Revised 2nd EditionCore Mechanic
Roll 1d20 to attack and meet or exceed THAC0 minus the target’s descending Armor Class. Ability and proficiency checks roll a d20 against an appropriate score. Spellcasters choose spells to memorize before casting.
Best For
Groups who want referee-led fantasy campaigns with class-and-level characters, prepared spells, optional proficiencies, and detailed combat procedures.
Highlights
THAC0 expresses attack chances as a single target-number calculation against descending Armor Class. Parallel PHB and DMG organization and a DMG index covering both books make rules topics easier to locate. Optional proficiencies add chosen weapon and nonweapon capabilities to class-based characters.
Considerations
Core rules remain split between the Player’s Handbook and Dungeon Master Guide, including DM-only procedures. Descending Armor Class, initiative modifiers, and special combat procedures require reference beyond a basic d20 roll. Optional proficiency rules increase character choices and exception handling.