Increases the damage done by your Immolate spell by X%.
Improved Immolate is a talent that increases the initial and periodic damage of Immolate.
A fairly vital talent that lets you get to Conflagrate and increases it's damage due to the new mechanic. By itself its a very good boost of damage to immolate if you aren't planning on going deeper into destruction.
Patch 3.1.0 (14-Apr-2009): Now increases the damage done by your Immolate by 10/20/30%, rather than just the direct damage.