Straight from the 1.4 patch notes (and just a little FYI, Lost island isn't an operation).
Mistyped, but, uh, thanks.
ok lets take out all the irrelevant information and I'll respond to the parts that have bearing.
LR-5 Sentinel Droid's Discharge now gives players a 3-second warning in Hard Mode before activating its ground effect. Players can now move the impending effect away from the group or tank.
Utility change, neither nerf nor buff and not enough time for the size of the effect
Plasma Arc no longer has an activation time and is executed while moving,
buff not nerf
and Incinerate is correctly marked as area of effect damage.
no bearing, just a tooltip
Plasma Arc losing its activation time is most-definitely a nerf. It used to screw up the ability of the tank to position the thing. Tank would be dragging him, he'd stop in the middle of a bubble and the tank would potentially have to eat bubble damage or risk an incinerate going off while out of intercept range (in some cases...note that I'm just talking about problems people did run into while learning the fight, not problems they should have run into if the tank was doing it right).
And the 3 second warning is also big. When the FP launched, there was no such warning and, for half the people trying to do the thing the first plasma arc would be invisible because of the crappy engine.
But I feel there have been more stealth nerfs to HM LI that haven't been listed in those patch notes. Savrak's spit is something else that seems to have been nerfed even in Hard mode. Used to be tough-ish to heal through. Now, it's nothing. His enrage also seems more lenient.