KarinsDad said:
Typically, the PCs have a horrendous time finding out tactics of enemies. Sometimes it is because they do not know who their enemies are, or where to find them, or by the time they find out who they are, they are already fighting them, etc.
Unless the DM drops clues like gumdrops, all of the campaigns I have been in required that the PCs work hard in order to acquire significant knowledge like BBEG tactics.
Even then, I cannot recall a single session where significant BBEG tactics were actually discovered (the BBEG lives in a fortress with xyz defenses, etc.).
Really? In our last Eberron game, both the PCs and the Villains scried each other REPEATEDLY before final confrontations. The PCs got the idea because the villains were doing it to them.

In my games, if the PCs take the time to engage in scouting, scrying, gathering info, they find info about resources, forces arrayed, tactics, etc. If they don't bother, they take what they get, sometimes VERY strong opposition.
In one situation, one Ethereal artificer took out a party of FIVE NPCs of two levels below him by himself, because the villains were caught off guard and had no divinations up (he used Superior Invisibility, and WASTED them one after the other. By the time the villains had figured out what was going on, and cast their true seeings, over half were dead, and only two escaped.
In the final conflict of the campaign, the PCs scouted the villains up to three rooms ahead in a dangerous demonic palace, before confronting them. The final fight saw the heroes surprised because the demons they faced had true seeing inherently, unknown to them, and walked right into a trap. However, because they used scrying, Knowledge (Dungeoneering), and were loaded for battle beforehand, they still turned a really bad ambush into a victory. Had they not been prepared, they would have lost given arrayed forces.
So in my experirence, prep and divination is only as useful as the DM allows it to be, and if the DM is prepared to handle it, the players can find it all the sweeter when a plan DOES go off well.
KarinsDad said:
It's the nature of the beast. DMs (and hence NPCs) are not truly omniscient (and able to plan for every possible PC tactic or even most PC tactics) unless the DM "cheats" (e.g. the NPC makes the save, even though the DM rolled a one) or "fudges" and has the NPCs react perfectly on the spur of the moment (e.g. the NPC just happens to have the precise spell memorized that saves the NPC from certain death at the hands of the PCs to fight another day, even though the DM never wrote down that the NPC even knew that spell in the first place, etc.).
Correct; that's why the PC artificer succeeded so brilliantly against the five villains, because he was prepped and they weren't, and that's what I planned for. In another situation, however, the same player surprised me totally; He faced down a beholder, and while the rest of the party distracted it, shot it with an antimagic ray while his central eye was focused elsewhere. It caught ME flat-footed (not the beholder), and in the end he had eagles from a SUMMON MONSTER II chase down the slow beholder, running for its life, and they clawed it to death.

One 7th level spell, and the beholder might as well have failed a finger of death save, because it would have been a quicker death.
On the other hand, they were the ones who miscalc'ed when the common ethereal/superior invisibility tactics they had used backfired on them, because of the demons' inherent properties. However, it was to be a hard fight -- they were facing a cabal of the Lords of Dust, and stopping the release of a Rajah. Even then, they used teamwork, and it showed.