Dark Void

Ok..after DAYS of doing the Abyss, I finally found a combination that worked for me. I was not good enough to execute on any of the above strategies.

I ended up only toggling Low Tech and Legend..which only gave me a x4 multiplier instead of x6. I found having nightmare on too difficult to get me past wave 6 with a decent multiplier, and having time press on didn't allow me to build a huge multiplier on wave 7. I'll break what I did down wave by wave. The KEY to high scores is your score multiplier in the top right corner!

WAVE 1: Kill as fast as possible. try to leave with a multiplier of x3 or more.
WAVE 2: Same. You are trying to get to 35k for your first upgrade.
WAVE 3: Target the capital ship that spawns right away..then go for the annoying little guys. You might be able to upgrade after this wave. Do so if you can..it helps tremendously next wave.
WAVE 4: Kill quickly...espcially the shielded guys..those guys tend to bring your multiplier down.
WAVE 5: As mentioned before, target the archon near delta point asap. Then
WAVE 6: This is a VERY key wave..you MUST do well on this wave. I was never lucky enough to have the 2nd rocketpack upgrade by now, but if you do, you are practically golden. You really need to end this wave with a multiplier of about high 30 or 40s at a minimum...otherwise you are screwed...this means you need to become halfway competent at killing the shielded watchers...which were the bane of your multiplier.
WAVE 7: You are going to milk this wave for mines..as long as you possibly can. As mentioned above, kill 2 capital ships asap (you will certainly have 2nd rocket pack upgrade by now)..and leave one intact. Then just carefully follow the 3rd ship and kill its mines to slowly build your score and multiplier. Do this as long as you can....eventually, it will stop dropping mines. I went into this wave with a multiplier of about 40..and left with a multiplier of 80..it should have been higher..but I kept hoping it would drop more mines and I lost about 5 multiplier points. This will take 20 minutes or so. I lost alpha point in the process...he was sacrificed for the greater good.
WAVE 8: Kill stuff as fast as possible holding both trigger buttons down. You MUST keep building your multiplier up.
WAVE 9: Same as 8. Your multiplier should be in or past the 90s by now.
WAVE 10: Kill the watchers if your last 2 (or 3) defend points are in good shape...otherwise go after the archons. For me, I killed maybe a dozen ships before I had to beeline to point delta..which was taking a huge beating. In the end, as I destroyed the 3 archons, my multiplier was x105 or so.

Here is a breakdown of my scores at the end for comparison
(Low-Tech and Legend On)
WAVE01 - 2,800
WAVE02 - 14,700
WAVE03 - 37,450
WAVE04 - 30,200
WAVE05 - 66,100
WAVE06 - 163,500
WAVE07 - 550,050
WAVE08 - 703,350
WAVE09 - 1,002,150
WAVE10 - 1,246,950
Score Modifier x4
Total Score - 4,987,800

Again, if you are good, you can probably turn nightmare on...but i found that the shielded watchers in particular took me FOREVER to kill and constantly brought my multiplier down...and I would get to wave 7 with like...a x20 or less multiplier...with it off, I went into wave 7 at around x45...and I am now living proof that you DON'T have to have 3 multipliers on to get the acheivement.

Notice that I practiced a LOT with low-tech, time-press and legend on. TimePress in particular really helps you learn to kill stuff faster or you lose.
Also, learn to SPAWN CAMP! You should know that as soon as you kill a watcher in a wave, another one spawns from the exact same spot they always come from..learn where that is..as soon as you kill one, beeline back towards that spawn spot and take out the next. You should be able to get in a groove of killing the spawning ones quickly as they fly a set path and are much easier to kill. Abuse this!! This helped me tremendously in building a multiplier..

Good Luck. Don't expect for this one to come quickly..you have to put hours of practice in..and by then, you will know the waves, and the layout of the map like the back of your hand.

My stategy was to pick the Timepress, Legend and Low Tech Modifiers. Time press and Legend are your go to modifiers in this DLC as they hardly affect anything so its an easy 4x. Low Tech is odd, seeing as you need those points, but believe me you don't want to give the enemies any more health or make them harder or anything like that in this mission (In the Ghen Crag mission I picked Timepress, Legend and Nightmare) as this will be hard enough. You want them weak so you can kill them fast to raise that multiplier in game.

In mission strategy:
Don't board a UFO and upgrade your jetpack when you can. This is key, I could never get close to enough points if I wasted time boarding one. Once I realised this I jumped from being no where near to the low 4 millions instanty. A fully upgraded jetpack has unlimited magnetic missiles which you can spam to start killing enemies super fast. I finished the last wave with a multiplier of 99x, ending with a score of over 5 million. You want to have a score of 750 000 or higher by the end of the last wave.

Basically it comes down to killing as fast as possible, and practice a lot, especially if you're like me and were never very good at flying in this game. At the start of most waves the UFOs come from the same spot every time, boost straight at them head on, fingers on the triggers, go for the non shielded ones if they're there, you'll damage a bunch of them, and later when you have missiles even kill one or two straight away. Hit the breaks and circle round and start following one. Try to get behind UFOs and just follow it untill it's dead, I found that once you damage a UFO it starts targeting you a lot more.

Always be firing, I didn't remove my finger from the triggers once, especially useful when you have missiles, I can't tell you how many times Id perform a manuever or turn to look at my next enemy and I'd accidently hit or kill another. Use the look button a lot (RB i think) to get your sights on the next enemy, everytime I killed someone if there was not another UFO on screen I'd hold it down and swerve around to face it (still firing remember you could hit something).

In the wave with the walkers that fire lasers these are your number 1 priority, take them out fast. Once you can board it, board the head side, it's a faster/easier take down. Make sure you get out of the way of the laster though, don't try push it too far, I died at 4.4 mill on the last walker once because I waited to long, which was really infuriating. These are the enemies that can decimate your objectives health. Don't worry too much if you lose an objective, you can still easily make it.

In the waves with the big ships and smaller faster flying enemies concentrate on the smaller ones first. These will raise your multiplier giving you more when you take out that ship. It also lets the ships spread out a bit, meaning that you'll only have the one firing on you instead of three when you go to take them out. Once everything's dead do a run on the ships taking out the turrets, if both turrets blow up the ship automatically blows up. If everything's dead except one last ship then you can just follow it for a while from a distance if you chose. Taking out the mines it drops, to slowly increase you multiplier and get some extra points. Keep and eye on your time and kill it last for big point and multiplier bonus.

All of this combined with practice and you'll get it easy. Playing it over and over you'll get an idea when what spawns and where. It's good to remember where the mines spawn in the waves they appear in as once you've killed all the UFOs if you know where they are you can mop them up and raise that multiplier quickly at the end of the round. If you are in a hairy situation fly low and around the rock formations to regain health, especially in the later waves, you might lose some multiplier but it's vastly preferable from dieing and starting again.

Goodluck!

Edit: RadiantViper's comment has some extra helpful information I didn't put in my original post. Here it is for ease of use:

"Just thought I'd mention, the wave with the Archon you should go for first is wave 5, and wave 7 has the 3 battleships (where you can let the last one live and kill some mines for extra points/multipliers). Wave 10 also has 3 Archons, but I found I could kill all the small ships first and still have time to take them out.

I actually died literally right after I killed the last Archon (boosted right into the plateau lol), but it still went to the 'mission complete' screen and I got the achievements :D"

A few changes to Phr4nk0's guide above i realized that with the time limit on there was no way to get this done, the people who did do this achievement with those handicaps are gods of dark void so instead of the time handicap i exchanged that for the handicap hardcore with enemies having more health, you just need to keep your ships alive and i only upgraded my jet pack once and your thinking well how did i get a high enough multiplier with enemies having more health... grinding mines dropped by ships in wave 7 as stated above kill 2 of the 3 ships and follow the last one for how ever long you need and kill mines to raise your multiplier up this method works like a charm... so if your struggling with this achievements try it this way with the time limit handicap off.

NOTE: You will need a pretty decent multiplier once wave 7 is over i would recommend as high as possible to be safe around 80x plus and you will get pretty insane point increases in waves 8-10 but also as a note doing this strategy will cause a ship to be destroyed following a mine ship around but do not worry as long as the others are good and despite grinding these points in wave 7 still do your best to finish earlier waves as quick as possible because killing mines and archons in wave 10 are faster with at least the rocket pack upgraded once..

Credit for this alternative way goes to Kindness123 for pointing this way out to me.

I found 2 better ways to deal with archons, more safe and quick. Both requires Hypercoil. You can replace your primary weapon in the update menu betweens waves.

Method 1:
Boost and fly to the archon and try to land near it. Don't shoot in the air or it will shoot back. You want to land with as much health as possible.
Once you lands take one of its leg as a cover and charge your hypercoil. Then just shoot the leg in front of you, which you use as a cover. You need to hold RT to keep shooting till hypercoil overheat, the archon will die before the second full shoot.
The archon will turn around so you have to move with it. It's machine gun is not very powerful but if you don't try to hide you will probably die before it.

Method 2:
Use your rocket pack machine gun/missile to blow up all 4 red spots. Then land or hover near it. Charge hypercoil and shoot, the archon will die before a full shoot.

I use method 1 in wave 5, and method 2 in wave 10.
Because I have missile update in wave 10 and it's quite fast to blow up red spot. And the default hypercoil ammo is just enough to charge 5 shoot.

There seems to be a lack of video guides for Dark Void DLC but I managed to find one on Youtube...

To achieve this high score I actually used the Wave 7 'Mine Farming' method (thanks Teamlead Taco), but still found it helpful to watch this guy in action and see how quickly he cleans up.

After watching his speed & practicing a bit, I was able to maintain a much better multiplier in the early waves & upgrade my Jetpack a little bit sooner - this makes all the difference!

Anyway - check out this Pro & good luck guys...

I finally got this achievement all I really did was abuse where the enemies spawn from. I used time press low tech and legend did this without getting the second upgrade for jetpack had 4.5 exactly and Im not even good at flying so for ppl still trying for this follow the guides above cuz they work. And on wave 7 farm for mines aswell to build your multiplier cuz my multiplier really wasnt that high. Mines was about 60. U just have to be accurate and fast