Move through Cover question

[fritzthedwarf]

I want to ask the community how the following is interpreted with regard to 'Move through cover' and assaulting.

Example - Genestealers with 'move through cover' assault through woods. Normally a unit rolls 2D6 and takes the highest. With move through cover would the stealers roll 3D6 and take the highest? It seems logical since move through cover means the unit should move more effectively through terrain but I'm not sure if that is what is allowed.

[redshirt2375]

"Move through cover" allows the unit to roll an extra d6 anytime it's required to make a difficult terrain test.
The test you take in the assault phase is a difficult terrain test.
Therefore, you roll an extra d6