Velocity is a property found on certain bows that was introduced with the Mondain's Legacy expansion. It can be described as a reverse of the Harm spell. For every tile away your opponent is, +1 damage is added if a shot hits with Velocity. So if you opponent is 2 tiles away they can be hit with 2 extra damage from a Velocity strike.
The following resources are required to imbue the highest intensity of Velocity (50%):