I fight lost wars, see light, fear sight
I open my mind, need flesh, fear mine
When you roll a 0 you kill the space marine that is now in the position that the green marine was in previously. Thematically the charge has gone off and it blew up the marine that moved into the position where the charge was placed. This is done after movement and activation so everybody is in their new positions.
An example would probably be best:
Before the move you had this situation:
After the move you have:
You roll a 0, the Yellow marine is dead and you do normal shifting of the formation.
Ah thanks for that. Much less paradoxical.
The terminator who you switched places with gets blown to shreds!