Door defence

Head for the door and see if you can defend from the passage within, as a horde of enemy try to come in and get you. Hectic stuff! It can be quite hard to find enough time to recharge your shield, but grenades can often buy you some time. You probably won't want any Hunters in this battle; they'd be a bit too troublesome in that cramped passage.

Plasma weapons are the probably the best things to have here, though you could risk using a rocket launcher if you're careful about using it close up. When there aren't too many enemies rushing me at once, I also like to use a needler.

Make good use of grenades. You're unlikely to run short of them with all the enemies you'll be killing. It's probably in your best interest to keep the passage fairly clear of loose grenades to guard against getting caught in a chain reaction - which is all too easy.

When there's a lull in the action, you might like to advance to the door to attack enemies heading your way. Pre-emptive action!

Checkpoint consideration

When you use this plan you can trigger a checkpoint, namely the one you'd normally get in the passage after leaving any Marines behind. Specifically, it's triggered in the short second section of passage. After reaching the door I suggest you try and get that checkpoint before enemies arrive (shouldn't be a problem unless they're already too close). It can then serve as a handy battle start checkpoint for temporary replaying. If you don't do this you're likely to trigger and get it sometime during the battle, and as such, you'd lose the ability to revert to the battle start (you'd need to eject the disc and reload).