[Verizon Samsung Galaxy S 4] G.moe:
This works for me on NC5, NK1, and OC1(NK4 bootloader).

Here's my process for getting an NK1 MultiROM environment:

Go to DL mode and flash to NC5 using the full-wipe tar as well as the .pit file, as per [MENTION=4939386]Surge1223[/MENTION]'s tutorial.

Let the device boot to the Setup Wizard, skip everything until at the launcher, and then let the device sit for 5 minutes.

Checkpoint 1 - 100% stock NC5. Woo.

Attain clean root on NK1 via [MENTION=4708661]muniz_ri[/MENTION]'s tutorial (I Odined the NK1 update tar; quick and easy). IF YOU HAVEN'T CLOSED ODIN SINCE FLASHING NC5, MAKE SURE YOU UN-CHECK "RE-PARTITION"

Checkpoint 2 - 100% stock NK1, rooted w/ SuperSu. Closer...

Reboot if you didn't after configuring SuperSu, and open it again to make sure Knox is disabled (or disable it manually when you're on the NC5 kernel).

Install and configure BusyBox and FlashFire.

Open FlashFire:

> Full Wipe, including internal storage

> Flash [MENTION=4055140]reggie cheeks[/MENTION]' Empty Galaxy - I'm using EGRFKK51S; it isn't Material Design, but it's fast and stable.

> Flash SuperSu

> Flash NK1 Modules

>> Lightning bolt to flash!

Now, wait until FlashFire is done, and you'll get the yellow triangle.

Battery pull, boot to DL mode and flash the NK1 kernel with Odin.

Once the rom has completely booted, open SuperSu and configure.

Reboot, install any updates from the Play store (Google should be the only update if you used an up-to-date SuperSu zip, possibly Nova Launcher), update Google Play services (open the Google app), reboot again.

Checkpoint 3 - Debloated, rooted NK1. This is a pretty good setup; consider quitting while you're ahead.

Open Root Browser, but say no to downloading the extra utilities (they can be downloaded later, and MultiSystem includes a newer verison of BusyBox), and install the MultiSystem apk.

Open MultiSystem, press Update Configurations, grant root privelages, press Install.

Install FlashFire.

Open FlashFire and flash the MultiSystem zip.

When the device reboots, look for the green LED; this will let's you know that MultiSystem is present and (most-likely) configured properly.

This is what I am using as my stock slot for MultiSystem; it's stable and can act as an excellent base for flashing other NK1 roms with MultiSystem/FlashFire later.

Checkpoint 4 - Debloated, rooted NK1 with MultiSystem installed.

Go to Setting > My device > Display, change screen timeout to 10 minutes.

Open MultiSystem, go to the settings, and turn on Run On Boot. Go back to the main page.

Turn on Wipe Cache and Wipe Dalvik; press Wipe.

Press Create Virtual IMG to make an IMG from the current (stable) stock system. You'll notice a red LED turned on; the process is not ready until this LED has turned off! Make sure you keep the screen on/alive until this has finished.

Once the LED turns off, open Root Browser and copy the IMG (located in /MultiSystem/img/system/) to your SD card or elsewhere, as this is your clean, stock img.

Install a terminal emulator, open it, type "su", press enter, grant root privileges.

Type "MultiSystem status" and press enter. It should say you're running Stock from /dev/block/mmcblk0p16.

Go back to MultiSystem, turn on Virtual System, and press Update Configurations

Under Primary System IMG select the stock img you just made, and press Update Configurations.

Press Wipe, and power off the device.

Power on the device, and when the green LED appears, press Vol.Up to boot into the Primary Virtual System.

Open your terminal emulator, type "su" and press enter, type "MultiSystem status" and press enter. If it says /dev/block/loop0, you're successfully running off the virtual slot on your SD card!

Checkpoint 5 - MultiSystem with debloated, rooted NK1 in the stock slot and virtual slot.

So from here, you can choose between the two systems at boot by pressing Home or Vol.Up at the green LED for stock or virtual 1, respectively. If you choose to use the second virtual slot, you'll use Vol.Down to boot to it.

You can flash most NK1 roms (if they mount /system appropriately) to a virtual slot by loading to the virtual slot, and flashing with FlashFire, wiping everything but Internal Storage and 3rd party apps. If you are flashing a similar rom, you can probably get away with only wiping dalvik/cache.

If you mess up your virtual slot, you can replace the img with a copy of your clean, stock img, and start fresh.