Nature Structures

I apologize, but doesn't hypnosis work regardless of the line of sight? That is, regardless of whether the creature/hero can see the mage or not? After all, hypnosis affects the mind, right? I haven't played in a while, I don't remember, but I think that's how it works. And therefore, it doesn't matter if the druid was covered or not.

Hypnosis requires a line of sight! ;)

although...
hey, what version of Heroes 4 did you play?
if I'm not mistaken, in the official versions, hypnosis and teleportation don't require a line of sight. But in the expansion, a hidden stack can't be reached with hypnosis, teleportation, and other spells that work without a line of sight in the original versions.