Goodusa, along with Lavavein, gets harder to deal with the more monsters are slain in the dungeon. Goodusa gains both physical and magical resistances dependant on monster level, which considering its high damage and high health becomes a serious problem. Thankfully, resistances can just as easily be stripped away, via any form of Might, the Piercing Wand or boons like , meaning that you do have a way to undo Goodusa's perks, unlike with Lavavein.
Death Gaze is the true problem. Goodusa's high stats paired with 100% Death Gaze makes for a cruel combination that can end the run even if you've managed to take down Lavavein with no difficulty. Spell casting would be the way to go, except for its high health, and relying on that alone will leave you nothing to work with on the other boss ESPECIALLY if Goodusa's resists have built up decently high. Very few strategies outside of poison or an incredibly strong spike will efficiently take Goodusa down.