Some hard-bitten troops are able to regroup more effectively than others.
Where your detachment has the Regroup ability:
When you roll to remove Blast markers in the Rally phase, remove an additional Blast marker. That is, remove D6 Blast markers rather than the usual D6-1.
1. Difference from Epic 40,000: We derived this ability from part of Epic 40,000's Dark Angels Deathwing ability. This allows for more flexibility in detachment design.