Measurements of probability to win in DnD-style battle

The most of d20-based systems uses next rule:

• throw d20 and add modificators to attack an attribute;
• throw d20 and add modificators to calc the defence;
• compare:
  • if attack is more - attack wins
  • if attack is equal or less than defence - defence wins

This repository contains some scripts with logic to calculate probability for attacker to win against a defender with defined dice parameters.

Probability to win the attak:

Probability to roll less than:

Probability to roll exactly: