These units have some special means to disrupt their opponents in close combat.
For example, forces of the Chaos god Nurgle often carry potent daemonic plagues which corrupt and debilitate those who come into contact with them.
'CC Blast' and 'FF Blast' are temporary names — we hope to settle on better names for these abilities in future. In a perfect world, these abilities will have names that are evocative and yet which also neatly hint at the relatedness of their distinct yet similar gameplay effects. Easier said than done!
Where your detachment has the CC Blast ability and takes part in a close combat:
At the end of the CC3. Roll to resolve the close combat step, place one Blast marker on each enemy detachment that had any units in base contact with units in this detachment. This effect does not stack with other detachments that also have the CC Blast ability.