knowing how to use the LB should be a requirement for all DPS classes, healers and tanks depend on the DPS to deliver the LB in the right moment. A lot of people use LB has a sort of finishing move but be careful not to cast it if you can build another bar. I wouldn't mind a caster using his AOE LB on a large trash pull especially if the tank pulled to much, so i guess you can use it to save the party as well