HOPE Vol.4
When it comes to the Magus Falls, it is a place that you can’t do alone. My advice to you would be to ask on the map chat. Also, you can use the lfg tool to look for people to help you. I am sure that there are alot of other people with the same problem as you are. One other place to look is in the gw2 wiki page. It has a lot of information on enemies and their locations. I did some looking, and the mushroom is in Nuhoch Lane at the Tangled Depths. The Veteran Deep Cave Troll is in the Tangled Descents. That is the first area you are in when you enter the Auric Basin. Good luck!