Horde boosting

Posted January 12th 2006

The basic idea

In a normal spiral path megabattle there are three groups of territorial enemies that remain pretty much where they are (occasional wandering aside), obliging you to go up to kill them. Specifically, there's an Elite with Grunts near the top of the path by a tree, then some Jackals near the cliff-edge rock by the pass exit, and some Grunts near the pass exit. Also, quite often there will be other enemies who despite having no such territorial limitation, hold back from the initial attack, probably hanging around in or near the pass. They might form a second attack down the path at some point, or they might just stay up top until you come up to get them. This is all good fun and gives you some variety, but it also lessens the intensity of the main attack down the path.

Horde boosting is about getting potentially everyone to join in one massive attack, or to accumulate behind a blockade if you've set one up. The method is basically to trigger a later checkpoint than normal, causing a change in enemy behaviour that makes everyone head for the underpass. These boosted hordes can give some fantastic battling, particularly with blockades, and there are other benefits too. In particular, the altered enemy behaviour allows some novel battle plans, you can bring extra Marines to the party, and you can arrange to play without music if that's what you prefer.

The one drawback is that with these higher enemy concentrations, you may get some noticeable framerate slowdown, particularly when close up to the enemy. Bungie probably never expected you to be fighting off fifty-odd Covenant at once! A degree of slowdown may also be arising from having triggered later areas, even if you kill the enemies there. Overall though, things are usually not too bad.


The idea of starting from a later checkpoint was originally used in Ice horde carnage, to get a huge mass of enemies packed behind a blockade down on the ice, ready for a spot of cyborg mischief. But then I realized it had a lot more potential and created this page to talk about it more generally.

Zigzag path trigger and checkpoint

In this section I'll give the specifics of the method.

Triggering underpass guards first

Before you can effect the change in enemy behaviour, you'll need to to trigger the cloaked guard or guards who spawn at the back of the underpass (two on Legendary, one otherwise). If you've spawned and killed the Hunters as usual, what I'd suggest is that you fly over the underpass, dismount and go about a metre inside. That's enough to spawn him, assuming you entered the trigger zone for the underpass checkpoint earlier when killing the Hunters (but if you didn't enter that zone you'll need to go further inside, reaching the rock near the entrance pipes). You can then head back to the Banshee.

However, another way of doing things is to land at the back before getting the Marines and Hunters spawned. If you then dismount and go right through, you can spawn the Marines and Hunters (there's a line you need to cross) then head back to the Banshee. The Hunters could either be killed later or you could take a few moments to do it the moment they spawn.

The zigzag path trigger and checkpoint

Once you've triggered the guard or guards, you can continue on to the 'zigzag path trigger' at the start of the short zigzag path up into the next snowy area. In a Banshee you can just fly low overhead. Some new enemies spawn and there's a checkpoint due afterwards, which is typically what you'd use as the starting point for your battle. You can keep it delayed (with Banshee fire or jumping) until you're back in the spiral path area if you like - though whether the game subsequently grants you the checkpoint promptly will depend on whether the Marines have got into any fighting. If you don't get it when you want it, you'll just have to try again.

Usually you should be able to get back in time for the incoming attack, though you may not be able to take up as advanced a position as you might like. Of course, if you've arranged a blockade to stop the enemy in their tracks, you won't have to worry about getting back quickly at all; you can take your time.

Altered enemy behaviour

The significant thing about the trigger is that it alters enemy behaviour. Consider first the enemies who've come through the pass entrance or spawned beyond it. Prior to the trigger, you tend to get a free-roaming mass that chases after you, plus lots of enemies who hang back, either in the pass or up on the cliff, but who may come down the path eventually, perhaps forming a secondary attack. There are also some groups which tend to stay in their own territories: some Grunts near the pass, some Jackals at the cliff edge near the pass, and an Elite and some Grunts by the tree near the top of the spiral path. After the trigger however, there's a general desire to head for the underpass, though some enemies in the pass may not move (particularly Hunters). You'll consequently get a larger attacking horde - potentially everyone flocking down the path - giving a less fragmented battle.

Now consider enemies that were outside the pass. Prior to the trigger they can easily be tempted into the pass, either by your proximity or by flying beyond them as if leaving the coast invitingly clear for them to advance. After the trigger however, they seem to have little inclination to move.

NB: In view of all this, it's best if everyone has already been tempted into the pass and preferably right through it, so they'll be part of the mass that heads for the underpass. This is what you want for horde boosting to work to maximum effect.

Eliminating the new enemies

Other enemies spawn at the same time as the underpass guard or guards (a Shade gunner on the roof and a squad near the start of the twin bridges area), and at the zigzag path you'll trigger new Grunts. It's probably a good idea to kill all new enemies if you can afford the time, as it should give the game less to deal with and may lessen any framerate slowdown experienced in the battle. In regard to the roof gunner, you could blast his Shade over before he even spawns, so he won't be able to use it on you.

Stopping the music

If you're flying low over the zigzag path to do the triggering, and if (like me) you fancy battling without music, continue on a short way, far enough to trigger more enemy. It's enough to fly around the big tree straight ahead. This further trigger causes the music to stop within a few seconds (but on the downside you've just given the game extra personnel to deal with, which might cause more framerate slowdown - I'm not sure).

Twin bridges Banshee pilot trouble

If you did some rearranging earlier and took the Banshee from the back of the twin Bridges area, remember that the pilot has the ability to materialize inside it if it's empty when he's triggered. You need to plan accordingly if you don't want him to steal his machine back.

Adapting normal saves

If you've got an old save starting with the underpass checkpoint, and you now want to try it out with this horde boosting method, but not all enemies were tempted into and through the pass, ideally you'll want to fix that so they'll be inclined to head for the underpass when you hit the zigzag path trigger.

If you kill off any loose Marines, it's easy to spend a while flying around trying to do that. If you've got loose Marines it's more awkward because they'll flock after you (or at least, they will whilst you remain in the spiral path area) and potentially get into a premature fight with the enemy. If you've got a blockade to hold back the enemy however, you can get around this by sealing off the Marines behind the underpass. Or you could lead them deep into the twin bridges area, then fly off to do some tempting, knowing that they'll take quite a while to get back to the spiral path area.

Using a blockade

Blockade set-ups are the most convenient to use for horde boosting. With the enemy held back (and possibly Marines held back by a separate blockade), you can take as much time as you want to prepare things before getting a battle start checkpoint. They probably also give the best battling, namely when you blow the blockade and defend against the suddenly released horde - something probably best done with a blockade which is quite a way back to give you enough time to work on the advancing mob.

Bringing in a Warthog or earlier weapons

If you're interested in bringing in a Warthog so it's always available for a spot of chain-gunning, it'll be easier than normal. Once you've triggered the enemy to advance to the blockade and seen them do so, you can fly off and fetch it. When you return, you can drive the hog off the cliff or the edge of the spiral path to get down into position without having to run a gauntlet of fire (assuming you put the blockade in an appropriate place of course). Spin as you go off the edge, to stabilize the hog, so you land on your wheels rather than your head. Another thing you could do is bring in some spare weapons from earlier, such as the rocket launcher at the tower. You can complete your set-up with a delayed checkpoint, either delaying the door checkpoint from the twin bridges area (preferably kill any new enemies you trigger) or a tunnel checkpoint.

Sealing off the Marines

If you've got a blockade to hold back the enemy, you have the option of sealing off the Marines behind the underpass before triggering your battle start checkpoint, by placing a Ghost across the exit after leading them through. The point of doing this would be to make it convenient to fight alone when you want to, namely by leaving them there (rather than having to kill them). When you want the Marines, you can easily free them by blasting the Ghost away with a Banshee bolt at one end (place the Ghost slightly away from the exit to make that easier). However, they'll take a while to file through and join you, which is a disadvantage to consider.

A couple of tips. Firstly, if you haven't already placed a Ghost nearby in advance when setting up your blockade, you can get one from the twin bridges area prior to triggering underpass guards. Secondly, when you arrange a seal, you'd best check that it really is a seal. Go to the other side of the underpass and hang around for a bit to check that no Marines are coming through. I had one case where they surprised me by getting through a gap I thought would be too narrow.

Bonus mischief

As a bonus you can do some novel things which are more along the lines of mischief than proper battling. One is that you can attack from the rear, and the enemy won't chase after you (except for raging Elites and Hunters) as they have an instinct to head for the underpass. It's great fun to send rockets skimming in low across the ground, taking out whole waves of enemy in one go. But for more on mischief see Ice horde carnage, the original situation in which I used horde boosting.

6-Ghost blockade on the cliff

One of the best situations I've had with horde boosting was with a 6-Ghost blockade on the cliff. Once I'd tempted everyone through the pass and triggered a mass advance, everyone accumulated behind the blockade (about 40 on Heroic; a few enemies had already been killed), and what fun we had! Well, me and the Marines that is. The Covenant didn't have much fun at all.

I'd blast the blockade with a Banshee bolt, then quickly land down on the ice somewhere and get ready to hold back the horde; maybe at the bottom of the spiral path, maybe at the corner of the ice path, maybe right back near the underpass (perhaps standing on a small rock there so you don't have to worry about idiotic Marines jumping in front of your sniper rifle or rocket launcher), or maybe up on a low ledge or something. There are so many weapon combos to choose from too, giving all sorts of different battles. As usual, you should kill your sniper if you want to make life much tougher. All this is just the sort of thing you'd do normally of course; it's just that you're up against more nasties this time, heading for you in a relentless stream.

I also enjoyed doing a ground attack from the rear whilst Marines were busy heading along, starting from the underpass. I had just a short while to work on the enemy, usually whittling down the Elites and Grunts with a pistol and dodging around, often causing Jackals to hit friendlies in the back with plasma balls. Don't you just love it when an Elite catches it in the back? Once the Marines got close, the enemy started turning around to face them, which was generally when I sent a few rockets skimming along the ground. Pure carnage. You can have plenty of fun with two-sided attacks like this.

Another little bit of mischief I had with this blockade was to try to mow everyone down with the Banshee, coming in just below cliff level then rising at the last moment, to minimize the amount of enemy fire. On Heroic it's possible, but you're sure living dangerously! As a variation on this, leap out of the Banshee before it blows, and drop a frag grenade to set off what will probably be a huge chain reaction. Oh, and then run!

Underpass attack

The altered enemy behaviour allows the following bit of mischief. Let the enemy accumulate at the underpass they were so keen to reach, and attack them from whichever side you fancy. There's plenty of evil fun to be had here with rockets and grenades. In particular you tend to get a big bunch of Grunts clustered around the entrance; so give them a rocket and listen to the delightful sound of multiple screams as they spray out in a big grunty fountain. Incidentally, there may also be a few Grunts that stop at the corner of the ice path, as if forming a miniature enemy outpost.

Sneaky tactics

You could also walk in amongst the enemy whilst cloaked, to do suitably evil things. If you're attacking from the exit side, one thing you can do is briefly pop your head around a big rock in the underpass to tag an unsuspecting enemy. The blast will usually take out a load of his colleagues too; it's pretty crowded in there!

With Marines

Attacking from the exit side, you can potentially have some Marine backup if you want it, namely if you made sure to lead the Marines through the underpass before the enemy started arriving there. Enemies sometimes get provoked into coming out to get you, where they run into a barrage of fire from yourself and the guys. Good fun with an assault rifle.