1. Work out the number of troops on each side. Anything with more than one attack counts as [number of troops x number of attacks], so 2 troops for a 2 attack monster, 3 troops for a 3 attack monster, etc.
2. Add the number of troops from both sides, divide by 100, and round down: this is the total amount of rounds in the battle.
3. Each side rolls 2d6 and adds the following modifiers:
- +1 positioned on higher ground
- +2 fortified (e.g. stakes, ditches, etc.)
- +4 strongly fortified (e.g. constructed fortifications)
- -1 outnumbered
- -2 outnumbered more than 2:1
- -3 outnumbered more than 3:1
- +1 better quality troops
- +1 more than 10% missile troops
- +1 each 25% of troops mounted
- -1 mixed species army
- -2 surprised or ambushed
- +1 each previous battle round won