So I am brand new to Descent and I apologize if this is a redundant or ignorant question. But starting out with just the initial intro quest where the heroes need to kill Ettins and fight Goblin archers I was immediately struck with a question that I have not been able to find the answer to.
The Overlord obviously knows where the heroes are and can just start moving the monsters to engage from all over the encounter map. But are there any rules to prevent that such as monsters having to hear something or notice something first?
In more complex quests with multiple rooms and doors how do you handle such issues? I could find no mention of it in the instructions.