Q26This might be more of a DM question, but I trust this board's collective take on the rules.
Here's the situation for a game tomorrow: the PCs (15th level, reasonably optimized but nothing crazy) are walking through corridors that have Guards and Wards cast on them. G&W lets you conceal doors w/ a simple illusion, but since nobody has a reason to randomly interact w/ the hidden doors it's a pretty solid concealment technique. True Seeing would foil it, but I don't think the party will have that up and let's assume not. Behind a couple of these doors is a Grisgol, who will want to surprise the party w/ a nice present of a Meteor Swarm.
Can the PCs do anything to avoid being surprised by this? If so, what? I'm leaning towards giving them at least a Listen check to hear the thing behind the door, since I want to be fair, but it seems like the set-up is bad for them in this regard.
Thanks