Okay.
R5-X3 is an astromech with the following ability:
Before you reveal your maneuver, you may discard this card to ignore obstacles until the end of the round
Since it's 'end of the round', not just 'end of the activation phase', it clearly affects the combat phase too.
This means....what?
- You will not take damage or other adverse affects from obstacles
- You may perform actions even if your base or maneuver template clips an obstacle
- You may perform attacks even if your bases clips an obstable
All those are fair enough and don't really need debating in my mind.
How about obstructed lines of fire?
- Can an opponent claim a bonus defence die? He didn't use R5-X3, so he's not ignoring obstacles, and it's 'his' roll, but he's defending against your attack and you did.
- Can you claim a bonus defence die? If you trigger R5-X3, nowhere does it say ignoring obstacles is then optional, even if the effect of the obstacle would be positive for you.