I was fighting Darius and got a little too big for my britches (I died - don’t judge :p). I ported back to the bridge before his room and all of the adds plus Darius were clamoring at the door. I unloaded my Fire Strike (rifle) and they all died…while interesting, I feel like I’ve cheated. lol
I’m assuming this is a known exploit?
Not surprised they overlooked it. Who would feel the necessity to use an exploit against Cronley (No offense OP :p). They did however fix a Mad Queen exploit which is nice. She’s a little less dumb now
Fire Strike went off as I hovered over the door. Once I saw Eldritch starting to spread, it was pure curiosity.
I think having to die to really set this up doesn’t make it such an exploit…I mean, it’s certainly not on the level of the Mephisto moat trick.
I never liked using it except on my HC profiles
Hah, there are so many ways and spots to cheese it but my favorite is using the enemy AI against itself. For example the Shambler just before the Flooded passage exit will follow you a while if you run away and then walk slowly back to his spawn point without doing anything while you attack him from behind. Cheap I know but hey, my casters thank the gods of broken AI!
I had the reverse happen this afternoon. I was clearng the Aetherbeast just outside of Homestead. The mobs in the wooden jail-cell things were shooting at me, but when I shot back my bullets wouldn’t cross the wood barrier.
I felt as if Grim Dawnian karma had be satisfied. 
You can also enter the boss area, lure him next to the door, use your personal rift to go back to Cronley’s Hideout, walk once more to the boss area and kill him through the door.
Alternatively you can open the door and fight him somewhere else if you want. 
Mind…blown.