“ Thrown enchanted skulls make great necromantic 'grenades' releasing blasts of negative energy, incorporeal undead, swarms of flesh-eating worms, etc.”
“ A local fungus-breed explodes if hit or fallen upon. If there is any conflict between inteligent enemies,both sides are likely to use it to their advantage.”
“ A Deity of some sort has unleashed a plague of bookworms or something like that in the area. Almost all spellbooks are destroyed, along with bardic and historical books.”