Effects of mushroomancer

Blue mushroom = potion

Toadstool = immunizer

Nitroshroom = demondrug

Parashroom = armorskin

Mandragora = max pot

Devil's blight = dash juice

Exciteshrooms seem to give a random effect, could not confirm.

Edit: you can't stack the nitroshrooms and parashrooms with their normal counterparts - you do the same animation as trying to drink a potion while max health.

Edit 2: I should clarify, dash juice got nerfed in World. It only halves stamina depletion now. Same applies to devil's blight.