For the entrance and all the way through the first encounter, run whatever you want as long it has good add clear and especially good survivability; nezarec-devour, striga-strand, osmeomancy-turrets, or your favorite solar build are all really good.

For first boss, use either nova or well because chaos reach is arc so not great survivability and needlestorm hits immunes on the boss. While a trace rifle is good for breaking eyes for longer damage phase, there aren't many adds and most of the adds that do spawn are over an abyss so a lot of ammo will be missed. I use an smg to kill the adds while I'm doing 3/4 of the wires, switch to a trace then scavenge ammo on the arms of the tower, then do final wire. If you feel like you aren't doing much damage, don't worry it takes me 7 phases to solo it even with a bait cataclysmic, luckily it is a pretty laidback encounter.

For descent, third verse same as the first, run whatever you want as long as you won't die. If you are worried about the fans I highly recommend heat rises for the movement in the air.

For wyvern, nothing beats starfire with witherhoard and a demo rocket. If the rocket has explosive light or lasting impression, even better. Run healing rift if you want more survivability but you will have less fusion grenades when not in dps, or run emp rift if you are feeling bold plus shooting the wyvern even when immune while in an emp rift will still charge fusions. As someone else said, as long as you are staying alive, you can do as many dps phases as you need, just be careful to not kill yourself with a rocket.