NINJA GAIDEN II

For this achievement you have to obtain 2,000,000 karma in each survival mission, this is extremely hard. You have to be an absolute expert in the game to get this one.

Tips:
- Know when to attack/defend
- Whenever you see 2 essence floating, do an UT, but only when your karma multiplier is 5, you should'nt absorb green essence for an UT
- Stay on the move, you'll die pretty quickly if you don't
- Get your karma multiplier to 5, this way you'll only have to earn 2,000,000/4 = 500,000 karma, which makes it sound a lot easier. AND more important is, when you have completed the waves of enemies for the first time, the difficulty will go up from Acolyte - Warrior - Mentor - Master Ninja, and you don't want that, so you should get karma ASAP.
- When your karma multiplier is 5, absorb all essence, also the green ones
- Don't give up, if you get frustrated, quit, and try again later, there's no point in losing if you lost your focus.

Weapon combos (by Lord Terentius):
I've found that you don't really need to know +10 combos to do well in a Survival. Only a handful will do, but the key is knowing WHEN to use it. Below are some weapon combos that helped me get the All Gold Survivals achievement:

True Dragon Sword:
Izuna Drop - XYXXXY [Great against Gajas & Humaioids, but tricky to pull off]
Flying Swallow 3x - Jump toward YYY [you'll be using this A LOT - don't be afraid to spam it]

Vigoorian Flails/FAILS (lol):
Foe Destroyer - XXYY [This is fantastic against hordes of closely pack enemies resulting in high chances of Instant Kills]
Piercing Mountain (whilst on the ground) - XYYYYYY [If you're struggling to maintain a combo and need green essence FAST use this. One successful connection from this combo and you're looking at 17 hits. Once you go airbourne you have Invincibility Frames too so this is KEY against RPG Ninjas]
Piercing Mountain (airbourne) - Jump towards YYYYY [see above - If things are going VERY wrong, jump at an enemy with this]

Tonfa:
Demon Tears Kick - Toward XXXXX [propels multiple kicks towards an enemy sending them and yourself across the arena. Not an instant kill but helped me get away from trouble when surrounded]
Overlapping Storms - 360 Y [When surrounded either quickly perform this, or jump into a crowd of enemies. You'll get loads of hits and a massive boost to your combo counter. Plus it has I-FRAMES]
THE TONFA'S UT1 & UT2 TECHNIQUES ARE JUST BRUTAL!! USE THEM AS MUCH AS POSSIBLE!! They're perhaps the best delimbers around and even a UT1 will annhiliate a Dinomech.

Eclipse Scythe:
Jump XXY or XXYYY [This is all you need. Once the first hit connects you're in I-FRAME mode. Once you've killed an enemy, dash-jump away and repeat. Perhaps the easiest of the Survivals to Gold]

Blade of the Archfiend:
Mighty Zhong Kui - XYXXXX [This will cut ANYTHING to shreds and is almost a guaranteed Instant Kill]
Swooping Dragon Fang - YYYY [See above]

Kusari-Gama:
100 Flames - Jump YXY or YXX [2 massive strikes followed by a 360 spin of the weapon that provides some short protection from would be grapples
Thunderous Light - Jump YY [Just the one hit then a 360 spin... a quicker version than above]
Immense Tragedy - YYYYYY [A devasting non-UT combo, but a WORD OF WARNING... make sure you have plenty of time/space to pull it off as it takes a while to 'warm up']

Falcon's Talons:
Izuna Drop (airbourne) - Jump towards YXY [best humanoid killer in the game. Doesn't work against Gajas. NOTE: half the time you DON'T get the Instant Kill bonus... for that use the combo below]
Flame of the Chimera - Jump towards YXX
Izuna Drop [ground] - XX toward XXXXXY [this is surprisingly easy to pull off and works as an Instant Kill against ALL humanoids & Gajas]
Thunderous Lion Roar - Toward XXXXXX [ideal against a tough single opponent or closely packed group]

Lunar Staff:
Gleaming Shadow - XXY [a very quick & efficient Instant Kill]
Izuna Drop (airborne) - Jump XXY [unlike the Falcon's Talons you can use this against both Gajas & humanoids...HOWEVER it has a ridiculously short range and if you miss you're vulnerable on landing]
Heavenly Shadow/Izuna Drop - 360 UT + Y at the height of your jump [arguably one of the more useful UTs around as it allows you to complete the move in full. Remember to tap Y at the height of the jump against humanoids & Gajas to convert it to an Izuna Drop]

Good Luck! You'll need it! Do not be ashamed of yourself if you can't do it, this one is legendary.

Please comment before placing a negative vote so I can edit the solution to improve it, thanks.

Credit:
Lord Terentius:
For the tip on using UT's constantly when your karma multiplier is 5.

No healing items (and seemingly less blue essence than the story) makes these survival missions hard, they're honestly not nearly as hard as the other ones, but I find myself being grabbed or hit from off screen a lot more than I like.

A slightly cheesy way to get more karma is to use the Windmill Shuriken UT. Switch over to it as soon as the first wave ends and you have the 5x multiplier. It travels all the way across the arena and can often tag a lot of enemies, this is where most of your points will come from!!! Extremely useful against Rocket Ninjas, Archers, and Mages. In fact it can flat out kill nearly everything in the game with it's UT. It's not fool proof, because some enemies are capable of blocking it, whereas your weapon UT will never be blocked. Very surprised that this wasn't patched out, since y'know survival is meant to be one weapon only, but won't complain. If RNG is right, I can have over 1M essence from a 5x multiplier at the end of wave 3 because of the WS UT. A huge chunk of your karma will come from the Van Gelf/Garja wave, there's so many of them in that wave and the WS UT just shreds them to pieces, and it's easy to get some OTs in during their death animation too, ~90K karma from just one kill at a 5x multiplier (counting killing spree and instant kill bonus, along with UT and OT during their death). UTs with your weapons are fine when needed, but their animations can go on for awhile that you might be lessening the karma you could get from just doing WS UTs. That said, the lunar 360Y, tonfa, and scythe UTs are all excellent for racking up lots of karma.

Green essence drops more frequently when your combo count is higher, utilize combos with longer hit strings and shurikens to keep the hit combo going (it technically doesn't increase drop rates. Greens drop more frequently because blues and reds stop dropping once the combo count gets high enough). Though those lovely Tac Team Ninjas love shooting you and stopping it. If you're in a pinch, using Guillotine Throws against ninjas are a solid way of getting greens (and blues if your combo count is low)

If you don't have a 5x multiplier at the end of the first wave, restart. Ideally you want to get the 2M before the first Rasetsu (all weapons have a wave with it), but at the very least be there or within a few thousand after that wave, so you want to get as much as possible in the early waves. Just before you think that multiplier text will start flashing, drop doing OTs and UTs and do regular high hit combos to get more greens.

The wave after the Rasetsu is a great breather wave. It gives you either beetles or baby skeletons. Be careful of getting swarmed cause they do hurt a lot. The best use of this wave is to get more greens to drop. Easiest way is to spam your Incindiary Shurikens to get the greens, and some blues if needed. Once you get your 5x multiplier again, switch to the bow and spam UTs against this wave. For almost all of my missions, this is the wave I reached my 2M on, thanks to the bow UTs.

Rotate Y with the Scythe, Lunar, and Dual Swords give you i-frames for the duration of the attack, and is your best move against dog waves and can help in a pinch for anything else.

Speaking of dogs, do your best to save your single ninpo slot for dog waves (if applicable), but if you don't have ninpo for the dogs, spam your weapon UT like you never have before, especially for the kusarigama. Wind Blades are usually the best, but Inferno guarantees at least 3 kills. Wind Blades also can give a solid amount of blues and the occasional green essence, and opens up a lot of OT chances, if enemies aren't outright killed. Red essence is a very rare occurrence in survival, so if you ever see a red drop, use your ninpo immediately.

Wind Path is a huge asset here, use it when you can, because you will need to be moving around a lot. Opens up lots of on landing UTs, and stuffs attacks from so many enemies.

My stats and rankings from hardest to easiest mission, and some combos I found to be good:

Flails, 2.11M, 92 kills (try to not save this for last. Forward Y into OT, rotate Y, YYYY in air YYY on landing rotate Y, XX forward XXXYYY)

Kusarigama, 2.03M, 92 kills (UTs and YYYY, rotate Y, in air YXY)

Claws. 2.10M, 96 kills (Flying swallow into izuna drop, forward Y into OT, rotate Y, XX forward XYYYY)

Tonfa, 2.14M, 71 kills (rotate Y)

Dragon Sword. 2.06M, 70 kills (honestly anything that's not the ET is good here)

Lunar, 2.19M, 107 kills (360Y UT, or I like to call it spin to win, XXY, XX forward XXX, in air XYX)

Scythe, 2.12M, 103 kills (in air XXYY, YYYY, XXY)

Dual Swords, 2.07M, 96 kills (anything really, but YYYY and rotate Y stands out the most)