Ascending AC and Base Attack Progression

Overview

This rule replaces descending AC plus attack matrix/THAC0 with ascending AC plus level-based attack bonuses. It changes hit math presentation, not overall combat pacing.

Procedure

1. Use ascending AC targets for all creatures.
2. Replace matrix lookup with d20 + attack bonus vs target AC.
3. Advance attack bonuses by class level progression chosen by the table.
4. Keep all other combat procedures unchanged unless explicitly modified.

Why Use It

• Faster adjudication at the table.
• Easier onboarding for players used to modern d20-style targeting.
• Preserves old-school lethality and resource pressure.

Boundaries

• This is a notation and resolution shift, not a balance rewrite.
• Keep monster defenses and gear assumptions aligned with the chosen AC conversion.

See Also

• B/X Resolution Fragmentation
• Target 20 System
• Old-School Essentials Classic Fantasy Rules Tome