Phantom Dust

This was such a Pain in the ... What finally did it for me was an environmental. My build was the following.

3 Skill Arsenal.

Rapid Cannon x2/3
Heat x1
Stimulatex1 ( I would have rather had another Heat but did not have one to use)
Graceful Woods (I did not use them when beating the sisters)
Reduced Entropy x2 (THIS IS KEY!!!! This prevents any skills with aura 3 or greater from use)
Aura x21

Obviously, you have to get a little lucky on the starting skills (hit back for a second attempt at a good setup). What is good is if you can get a few aura particles and reduce entropy and heat. If you can get to 4 particles and use a heat quickly then use the jump and put the entropy in a corner in your rooftops. The sisters never went for it. They then had no moves they could use. Be careful not to use all your skills on the ground. I found it best to get heat so attack +1 and get about 10 aura. Then use up stuff until you have 3 white aura on the ground and leave them alone. The sisters will destroy attack/defense/etc auras but will not touch the regular ones. Since you only have 2 or 3 rapid cannons be careful since the sisters defenses can wipe them. I just sat around and the sisters would go through all their auras and then when they could do nothing they would just come stand in my base and let me kill them. The third sister i waited again till she had burned through all her auras and was just running around then i went in for the kill with rapid cannon.

Hopefully this helps. It made them almost pathetically easy to beat.

This can be earned during the mission Strange City: To the City of Memory. You can get this on a mission replay from the Simulator.

In my experience the best strategy is to use a Vibration Blaster deck. You'll have to be quick picking up your skills as the multiple Freia's will steal/destroy them. Use Rapid Cannon until your aura is high enough for Vibration Blaster.

The deck for this is quite simple:

2x Rapid Cannon
2x Vibration Blaster
2x Fortress of Iron
3x Level Amp
1x Level Boost
2x Graceful Woods
3x Heat
1x Stimulate

I used an arsenal with Memory Lapse & Regenerate. When battling the two Freia clones set the Memory Lapse and let them use up all of their attacks/erase skills. Use the level (fencing, etc.) to block attacks and you should be able to get them to use up all of their attacks. You may take some hits during this process, use Regenerate to bring your health back to 20. From there, you should be able to take the Freia trio down.

While I had a whole bunch of attacks in my arsenal - Hyperkick wound up being my go to attack?!