Just beat Amanithrax. I found this delve much more difficult than most who have written here—not sure why.
Went in with a Mushroom Man up top and 3 Gobtruffles (both at Gold-Elite).
Loops were hard to come by for whatever reason. Lost Mushroom Man in the penultimate battle of the run, and finished the boss room with only one Gob left, who would have died to a single skull or cast. Just got lucky that neither happened.
My only note of worth, I think, is that 3 Nysha medals are helpful to have equipped 
Level 15 Zaejin, and 118 Hoard 