Whatever wrote:If the party has access to level 3-4 spells, I'll assume the Druid does as well. That means Scrying, so the party either has amazing stealth (you'll need a lot more than just Silence) or gets ambushed like whoa, since the enemies know that they are coming.
The NPCs can easily have contacts in town who alert them when people show up to ask suspicious questions about this bell tower. That's both enough to start Scrying, and probably get some decent modifiers going.
I have no idea what a "psychic" is capable of (same with "shadow demon"), though, so it's hard to say what they'd add to the preparations. The dragon can contribute a bunch of useful magic items, no doubt, plus the whole flight/breath weapon/crazy melee routine (not sure why it'd be in range for Wraithstrike at any point).
The enemies in question were vaguely described as divinations don't just spell everything out for you. It takes some degree of deductive reasoning to work out what that stuff actually means. Even then you won't know, and have everything specifically countered which is also the point and is also the point of general purpose stuff.
Scrying first requires foreknowledge of who you should scry on and second requires you have that spell today. If the party fought, then withdrew Scrying becomes a reasonable possibility.
Contacts in what town? The only other things around are:
Various monsters that would like to eat their face. Where "their" means "both sides". Whether or not they are able is another matter.
Lizardfolk. Which live in swamps, much to grog's amazement. They don't have anyone that could scry and it's unlikely the party would go asking them any funny questions.
NPCs friendly to the party that would really rather have these guys gone from their lake.
The psychic was actually a psion who favored telepathy effects, so the Magic Circle prevented them from violently murdering each other.
The shadow demon they couldn't figure out, and so couldn't make special prep for but the general prep, combined with a broad array of abilities and learning as they went was enough. When you get hit with a long dot, stop dots. When the enemy can move through the floor, walls, and ceiling and attack at literally any angle... you might as well go out in the open, because everything is the open.
The dragon came out and fired off a Blood Wind full attack at 60 feetish. That's melee range if you know what you're doing. The point with that is that you just can't fuck around with dragons. If they get a turn, they'll spend it fucking up your shit so kill them before they can move (and since 1: Shivering Touch is banned. 2: Scintillating Scales, this is one of the places those Dispels help., the easy way is not quite as easy).