Just fought 3bug with randoms for 14 minutes straight and won
Went through 8 starlight shards casting a renalla's moon with the legendary staff and Restaging it(with the good 3+ staff and rise FP relic on) and the boss was still at 1/3rd health which had to be chipped away manually with a golden order greatsword.
Duchess might just be the queen of clutches if you know how to dodge.