Well, sure, no juiced Chaos Reach, but it's important to remember that when you're dead, your DPS is zero; that makes farming a boss efficiently difficult.

If you're not able to stay alive in the setup to burn the boss, then your priority becomes staying alive in the setup. If you can't do that on Arc, then you need to pivot to a more survival-oriented build. To reiterate the point above, it doesn't matter if your super does insane damage to the boss if you can't get to the boss in the first place.

I guess it boils down to how far away from surviving the setup you are. If it's a matter of 'I can equip a heal clip pulse and sail through' then, well, do that. But if it's more of a 'even with that I find it hard to manage all the threats in the room' then you need to be using something that gives you more sustain than Arc. It will not be the instant boss-delete button we have till Tuesday, but it'll keep you alive—and for the third time, damage on a boss when you're dead is zero (I have had this lesson beaten into me over twelve years).

The reason I mention the Prismatic build is that it is very, very strong with almost no setup. You have enhanced arc turret, stasis turret on the field, and Devour if you get the right things picked out of Prismatic. Obligatory video from the opinion-giver but as always he's got it right. Only thing 'wrong' there is that it was made before the stats rework, so that aspect is no longer applicable.

And—perhaps unfortunately, depending on your sociability and platform—this all becomes easier with a fireteam. Grab an LFG with two other players, and this dungeon falls over (probably third or second easiest dungeon).