There's a new boss/mini-boss critter (Kopru) in Isle of Dread with a pretty mean anti-melee ability called "Mind Seeker". It pumps out no-save no-spell-absorb force orbs about every 15~20s. They're highly likely to one-shot most characters.
Really bad design on that one there. It boils down to an anti-melee attack.
Some other notes that you might find helpful.
I never saw the attacks and assumed it was just a "reach out and kill you" kind of thing UNTIL I fought a Kopru on brightly lit white stone. THEN I saw what it was doing. It's a dark mauve nearly transparent orb that chases you much like a flame sphere, but faster and not forever.
If I was not in melee range (maybe cone distance?), I could see it and flee from it. But, as my char was melee and there's no telegraph or warning, it's essentially an instant-kill unless you happen to be 100% HP when it hits and able to instantly stack on something to save you (eg. guard-up TMP hp) and heal back.
IMHO, it's a decent way to spice up the game for ranged. Dark/dim surroundings or heavy flash/bang from group might make it VERY hard to notice, but there's a chance to spot and avoid.
Melee haven't a prayer. No save. Spell absorb doesn't work. No chance to see it before it hits.
BTW, that 2400 was non-crit on R4. Scaled up to R8~10, it will kill all but a soak tank or maybe a really beefy barbarian. My char was a rather stocky rogue with ~2800 HP.
How I worked around it solo'ing on R4 was to summon a herd of hires. If you stand a few inches behind the hires as you melee, the hire will eat the seeker. Ironically, the bad hire "AI" of crowding in between you and the boss actually works to your advantage here.
Now pray you can kill it before you run out of hires. Bosses in Dread have big HP -- 60~80s of hires might not be enough. Suggest planting a hire outside fight that you can run to for rez.