I got a buddy who plays Plague Bearers a lot and loves to glance my Land Raider to death with rusty attacks. Almost every game he deep strikes them in nearby and assaults my tank, getting his +1 attack for the assault. I usually sit there and take it, trying to get off as many shots as I can before it dies. But since I sit there, he wants to move his guys back 1" in his movement phase and then assault again for another round of +1 attacks against my vehicle.
This tactic feels kinda lame to me, but I can't find anything in the rule book that expressly says he can't do it. Is this tactic legit?