I am going to be yoinking that for sure, thanks.I built an adventure once around a lizardfolk lair in which they harvested a type of fungus which, when disturbed, produced Strength-draining spores. The lizardfolk, already aware of the effects of the spores, would purposefully disturb them when intruders invaded and then make use of their ability to hold their breath for a long time to make sure they were not affected by the spores, while the intruders invariably were.
If you haven't seen HBO's The Last of Us, that's used to very good effect there.So, secreting digestive enzymes sounds like an interesting attack. Being inconspicuous could lead to stealth fungi. Breaking down manufactured materials could damage equipment. Impacted food supplies could cause problems. I especially like the last one. As soon as one of them knows you're there, the rest of them do too.
I was going to post along those lines, but got beaten to it.Or perhaps the mushroom and fungi aren't the hazards at all. The nearly-sentient insect monsters that tend their fungal garden, however....

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.