Unlock Location:
- Progress through the story until reaching "One Fell Swoop" main quest.
- Go to Carcadia Burn and find the Crawlcroft Order Bunker
- Progress to the end to find Fractis, the boss who will drop
Protean Cell.
Farm Method:
- Defeat Fractis.
- After use the Encore Machine nearby to reset the fight.
- Repeatedly defeat Fractis until Protean Cell drops.