Damroll is a straight percentage applied to your base damage. Ten
damroll would equate to 10% more damage.
Damroll is effectively uncapped at this time.
For level 50 characters, damroll starts at 0.
Damroll increases by 1 point for every 3 points of strength over 30.
Damroll is increased based on bonuses from worn equipment.
Damroll is increased based on bonuses from spells and skills.