Every time the Storm Rider ability is used, it increased the current DPS by 10%; after use there is an 8 hour cooldown period, this may be reduced by the use of trinkets that can be found within chests and upgrading Storm's Building talent.
The Magnify skill used by Detective Kaine (and others in his bench slot) increases the effect by 50%, resulting in 15% of total Damage Per Second added. Therefore, as Storm Rider has relatively long cooldown, it is recommended to use Magnify before casting Storm Rider.
Storm Rider can only be used when Thalia, the Thunder King (or another Crusader in his bench slot) is present in the current formation. However, the effect of the ability persists even if you remove these crusaders from your formation. The effect of Storm Rider doesn't stay after you reset. (Bug is now fixed in v0.32).