Unlock Location:
For the sake of story spoilers, we've left the specifics intentionally vague.
Plasma Coil is not farmable until you beat the campaign, but can be found as a World Drop.- Progress through the campaign and take on "The Timekeeper's Order" Main Story Mission.
- Travel to the Upper Dominion in Dominion City.
Farm Method:
- Defeat the Timekeeper during the Story Mission.
- Utilize Moxxi's Big Encore Machine to farm until Plasma Coil drops.