Setting up for a small squad
Here's how to set up battles that feature up to five Marines, namely the guys that spawn in the spiral path area.
- Creating a base save
- Finishing from the base save
- Dealing with premature enemy threats
- Getting all four Hunters
Creating a base save
First you should create a base save which covers most of the work, allowing you to then produce multiple battles quite easily. In the base save described here, you'll end up with as many as five spiral path Marines neatly sealed off after the underpass. There'll be a load of enemies held back by a blockade in the spiral path area, but you won't have triggered any enemies in the twin bridges area yet, nor even the underpass guard or guards. You'll be ready to build a pen or blockade in the battlefield, having assembled a pool of material to use. You'll have two hogs in the battlefield, and potentially also some spare weapons to arrange as desired.
The main description here involves doing a descent trick off the first bridge, but it's also possible to do things without a descent trick, as detailed at the end of this section.
Do some early rearranging
Start by doing a descent trick at the first bridge, so you can do some rearranging as follows.
In the twin bridges area (where you can get your first Banshee), assemble building material for pens and blockades. See Ghost provision for some useful advice. You could also overturn the Shades to prevent them getting manned later.
Leave a Ghost just after the underpass exit, for later use in blocking Marines once they're through. Preferably also have a second Ghost on hand for later use in blocking the zigzag path, to keep Marines back while you're building a pen or blockade.
Preferably also assemble some spare weapons (some of which may just be place-holders for UNSC spares that only become available later).
In the spiral path area, build a blockade across the flat ice path. This will have the dual purpose of minimizing any Marine advance when they spawn, and of subsequently holding the enemy back once the Marines have retreated through the underpass. The Marines appear in the shadow, so build it along the shadow-line itself. If you want to save your Ghosts for the battlefield, two Banshees and two Shades can do the job.
Don't use the twin bridges Banshee as blockade material; keep that one for flying around in. You'll probably later want to be in it when triggering its pilot.
Tip: If you now get a tunnel checkpoint and save a copy of what you've done so far, you'll be able to use that copy later as a time-saving starting point for creating a base save for battles with a large squad.
There's no point putting a hog in the twin bridges area yet, as the game would just move it back to its original position when you trigger the first ground battle. You'll bring hogs along later. The hog blasting method for getting a hog into the spiral path megabattle can be used. Ideally, prepare for that by leaving a Banshee near the exit of the rising tunnel, as described in that method.
Finally, prepare for getting an extra hog (back the current one down a passage).
NB: All this rearranging is a lot of work, so it's a good idea to save a tunnel checkpoint when you're done (or almost done), so you'll always be able to get back to that point if subsequent work goes badly.
Resume normal play and reach the rising tunnel
Resume normal play, letting all early Marines get killed (two groups). As you near the rising tunnel after the underground bridge, have both hogs on hand. You'll probably want to be carrying a sniper rifle.
Get the hogs into the twin bridges area
Whizz up the tunnel in a hog, transfer to the Banshee you left handy, overturn dropship Ghosts as usual before they get manned, then do your hog blasting to get the hog into the spiral path area. Remember to stay up high until past the tower, to avoid triggering any more enemies yet. Once the hog is well into the spiral path area and you're clear of the few pursuing enemies (who'll go no further than the pass for now), transfer to the hog and drive it into the twin bridges area. Fly back to the tunnel exit, still being careful to avoid triggering new enemies. Land and head for the second hog, either on foot or in one of the dropship Ghosts. Hop in and whizz up the tunnel. Switch to the Banshee and get the hog to the twin bridges area just like the first. Return to the Banshee and head back.
Maybe get some more Ghosts
If you want more Ghosts for building material, attend to it now. You'll be able to blast them along just like the hogs; see 'Late collecting' in Ghost provision.
Develop a spiral path megabattle situation
Do the usual work for developing a spiral path megabattle. You'll probably want to kill the two Shade Grunts in the spiral path area before triggering the Marines, but see here for full discussion (it's possible to get them into the battle). When it's time to trigger the Marines, first draw enemies well back towards the pass, to minimize the chance of hostilities breaking out with advance enemies. You want Marines and enemies undamaged. Preferably trigger the Marines by freefalling near where the Hunters appear so you can squash the Hunters instantly (see my refined routine for setting up a spiral path megabattle).
Get the Marines through the underpass and seal them off
To minimize any danger of advance enemies attacking Marines, quickly ascend and draw enemies well back towards the pass again. Fly high out of danger to get the underpass checkpoint if you didn't already get it when down near the Hunters. Preferably save the checkpoint. This way, if anything goes wrong shortly, you'll be able to return to this point even if it requires ejecting the disc and reloading (which it would if you get another checkpoint). All this is optional, but recommended.
Head across to hover over the underpass or thereabouts. Hopefully you'll see all the Marines starting to head your way, thanks to the blockade being so close. Back off further as they come, to draw them through the underpass.
Seal the underpass exit with the Ghost you left handy, to stop the Marines going back through shortly. But be careful not to enter the underpass even slightly, as you don't want to trigger the underpass guard or guards yet. Skipping that trigger prevents any enemies spawning in the twin bridges area yet, which will enable you to prepare your defence there. Also block the zigzag path with a Ghost, to keep the Marines out of the way when you're later building a pen or blockade. Be careful not to squash anyone when parking these Ghosts.
If you're never going to want the sniper in your battles, kill him (leaving you with a handy spare rifle). However, I suggest you keep him for now; you'll always be able to eliminate him when setting up a battle.
Finalize your provision of spare weapons
Earlier you may have left some spare Covenant weapons around as place-holders for UNSC spares that weren't yet available. You can now make the appropriate switches if you haven't already done so. But if you haven't bothered with spares at all yet, at least take the time to arrange some near the underpass, as in the basic plan.
Get a save checkpoint
To complete the base save, fly off to trigger a tunnel checkpoint, and use Banshee firing to keep it delayed until you're back at the battlefield, ready to start building a pen or blockade. Then save it.
Doing it without a descent trick
If you can't get off the first bridge with a descent trick, you won't be able to do the early rearranging work. You won't be able to get a second hog, and hence you won't have a Marine-retaining hog that can be used to get continued chain-gun support in battle. But you can still get by ok. You'll need to do a few things differently as follows.
The first Banshee you'll get your hands on will be the platform Banshee, which you should rocket down in traditional fashion.
To get the hog through to the twin bridges area, you'll still use 'hog blasting' but worked a little differently, perhaps as follows. Fly up the tunnel, having left the hog near the bottom. Overturn dropship Ghosts as usual, and wait for enemies to come out of the tunnel. Lead pursuers away while remaining high up to avoid triggering tower enemies. Then fly back and land near the tunnel exit. Run to the hog, drive it up, and transfer back to the Banshee. You can now start blasting the hog along. Try to minimize Banshee damage in doing all this.
To provide yourself with Ghosts to use as building material, you'll need to blast most of them along to the spiral path area like you did with the hog. Do this after getting the hog through. Some such collection was suggested in the main plan anyway; but this time you'd also be blasting along the four Ghosts parked around the tower. There's also the tower Banshee if you want it.
In regard to the provision of spare weapons, see my advice elsewhere on getting them without a descent trick.
Finishing from the base save
Here's how to set up a battle from the base save. You don't always have to use all your Marines of course; you can always eliminate some.
Prepare your defence
Build your pen or blockade and get the Marines confined. Except, it's ok to leave a Marine-retaining hog manned if you like; you could have a chain-gunner ready for battle in a supporting position. If you've got spare weapons on hand, arrange them as desired (think about where you might best like them). Maybe remove surplus objects.
Release the enemy and finish off as normal
Before this final bit, you may like to get a delayed tunnel checkpoint to potentially revert to if the work doesn't go well enough.
Fly back and draw the enemy well away from the shadow-line blockade, then blast it. Make sure the pieces are moved well off the beaten path, else enemies may get a bit stuck behind them. Draw all enemies completely through the pass (i.e. properly into the spiral path area), to help ensure that they all come down the path shortly, then finish off like in the basic plan, starting with triggering the underpass guard or guards. The only difference is that you may need to deal with premature enemy threats to the Marines when triggering enemies in the battlefield.
Alternative finishing, for advance elimination
In some cases you may want to trigger and kill some twin bridges enemies before bringing the Marines into the battlefield. It may be advisable for Marine safety, depending on where they're going to be. If you're going to do that, first make sure to draw all spiral path enemies completely through the pass (i.e. properly into the spiral path area), to help ensure that they all come down the path once their behaviour changes (it changes when you approach the zigzag path after triggering the underpass guard or guards). Also note that because of the behavioural change, you won't be able to tempt the spiral path enemies away from the blockade later on. Try to minimize casualties when you blast it. Actually you could instead make use of the active camouflage to release them: sneak up and bash a Ghost aside to open a gap.
Dealing with premature enemy threats
If you have your pen or blockade near a place where one or more enemies have yet to spawn, you'll want to neutralize the threat to the Marines, as you don't want them getting damaged before battle. Obviously one way is to trigger and kill the relevant enemies before bringing the Marines into the battlefield. But that pretty much forces you to kill all the free-roamers that spawn in the battlefield, else you won't be able to get the Marines confined in peace. As such, you'd be losing out on potential battle fodder. The alternative is to let enemies spawn after the Marines are penned, and try to kill the immediately threatening ones before they damage the Marines badly. The following techniques can help.
Ghost pilot near the back
A Ghost pilot spawns near the back, but if you've deliberately left his Ghost upright somewhere far off, he'll run towards it and you'll have plenty of time to blast him before he gets there.
Banshee pilot near the back
A Banshee pilot would normally spawn near the back, but if you've deliberately left his machine elsewhere, he'll materialize inside it, or by it if overturned, and you can kill him later. E.g. leave it overturned near the start of the area.
Grunty gunners near the door
Two grunty gunners materialize near the door, and on foot they have quite large territories that would make them a threat to Marines on that side of the battlefield. But if you've deliberately left their Shades upright somewhere far away, they'll go toddling off and you can kill them before they get there.
Getting all four Hunters
In the plan I said to squash the two Hunters that spawn with the Marines. With extra work though, it's possible to keep them alive so you get all four Hunters in the battle. You can do it like this. Leave a Scorpion and Shade just near where the Hunters will appear, so they'll be boxed in, and so the Scorpion will shield the Marines from attack. The Hunters will probably fire a few shots anyway, but if you can get draw the Marines through the underpass promptly, they can escape unscathed. It could take a few attempts though. Later on, you can move the Scorpion or Shade to free the Hunters.
Watch out boys
Whether you really want four Hunters is another matter, as Marines are rather good at getting blown up en masse by shots that sail in from distance. You'll need to be on the lookout, ready to take care of that threat if you can.