These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Big Lipped Alligator Moment: Towards the end of the first game you suddenly come across two intelligent species locked in conflict which have never been seen or mentioned before. You have to choose to side with one and decimate the other to proceed. This seems completely unconnected to anything else in the game.
Demonic Spiders: Many in every game. The Pentrogs in Opinwood and the snakelike apparitions in the White Tower in Lands of Lore 1, those freaky neon-pink spider thingies in at least one game in the trilogy.
Goddamned Bats: Those winged spiders and plague rats in the Draracle's Cave.
That One Boss: The Larkhon. The weapon you're supposed to use on it is not nearly efficient enough and eats the characters' mana; magic-challenged players may have to resort to just chucking items at it until it dies.
Made easier by simply dashing back out into the forest once you're low on magic, resting to fill up your magic meter (and restoring any health that's been lost), then re-entering the mines to attack the Larkhon again. Repeat as necessary.