Dangerous Terrain tests would still apply, Overwatch has specific conditions to be met for which movement count for allowing overwatch, from FAQ.
Quote:
Q: Does a counter-charge trigger Overwatch?
A: No. The “move” referred to in the OW rule refers to moves made as part of
an action, as described in section 1.7.
Dangerous Terrain tests have no specific conditions to be met for which type of movement trigger the test, it is only when entering or starting to move whilst in Dangerous Terrain that matters.
Quote:
1.8.1 Dangerous Terrain Test
Roll a D6 when you enter dangerous terrain, or when you start
to move if already in dangerous terrain. On a roll of 1, the unit
is destroyed with no save allowed, but the formation it is part of
does not receive a Blast marker.
Units may choose to move through dangerous terrain cautiously.
A unit that is moving cautiously counts as having a speed of
5cm, but is allowed to re-roll any Dangerous Terrain tests that it
fails.
To help me understand why I class it as the overwatching formation don't want to hit their own troops that are making the assault as they are too close for getting safe shots off (don't want to cause friendly fire).
