I've seen this asked a bunch on here, and other places so I know this sounds like a repeat, but I promise none of the provided solutions work.
There is a chest in the library with a pillar on the far side of a hole in the floor, and a quest for Master Darkin to get up real high and I cannot solve either of these puzzles.
To me the "obvious" solution in both cases was Misty Step, and that worked for a different chest in the Library near the one I mentioned above that is below the characters. I could Misty Step down to a chest, but not across the hole. I tried everything I could think of, I tried Levitate, but obviously that just moves a character higher or lower, they can't move side to side. I tried casting Jump on my High Strength character, but they couldn't jump across, even when I brought them up to the "ceiling" level. Does the Mage need to be up on that level for Misty Step to get across? That is the only thing I didn't try, but seemed like that shouldn't matter if they can't see on the same level?
Similarly I couldn't Misty Step up to the Tower entrance for Master Darkin's quest. I could Levitate a character up to the correct height, but obviously they can't do anything once they are up there. I got as close as I could for Misty Step but no dice. Is there somewhere else I should stand? I tried interacting with the "Minor Gate" that Master Darkin mentioned, but I'd already grabbed the plaque off it and I think given it to the Antiquarians, so hopefully that's not necessary. If it helps I can only just barely see the ledge with the glowing blue fire, even when I spam the scroll wheel.