The old dungeon crawl philosophy of going from room to room, kicking down doors and dealing with whatever’s inside one encounter at a time is very prevalent in the design of 4e. In some ways, it is even more pronounced. Whereas in older editions, to successfully overcome a particular encounter you might have needed something prepared beforehand – ropes, candles, 10-foot poles, particular spell, etc. (I’m speculating here, as I started playing with the release of D&D 3.0), in 4e pretty much any challenge PCs encounter they are expected to be able to overcome with just their innate abilities. Being perfectly spherical in nature as they are, they don’t need to bring holy water to a fight with a vampire. What happens if they do?
Sometimes, your players employ strategy to completely derail your prepared encounter, changing its very nature. But as often as not, they are willing to go along with your plan… mostly. They employ tactics instead. They study their opposition and come prepared, or at least they wish they could. There’s woefully little they can actually do in 4e with the knowledge of their enemies, but what little they can do sometimes completely unbalances the encounter nonetheless. It’s unsatisfying.
What can enterprising adventurers learn about their adversaries? Nature of their enemy, their composition, their goals. Lay of the land. Given good enough checks, players basically have access to their enemies’ stat blocks. From it we learn what the monster’s defenses are, and what defenses it attacks. The type of damage it deals, vulnerabilities and resistances it has. They basically learn, everything they would have learned the moment the combat started.
Pieces of a puzzle
One of the main components of the tactical variety of 4e combat lies in strengths and weaknesses each combatant possesses. Brutes have low AC but high Fort. Artillery have low defenses, but usually attack non-armor-defenses for lots of damage. Vulnerabilities and resistances also fall into this category. And the key to winning any encounter is hitting enemies’ weaknesses with your strengths, while preventing them from doing the same. You send the cleric with his radiant powers to deal with shades while the fighter draws the attention of zombies, who flail at his high AC ineffectually, the wizard fries their miserable Reflex with fireballs and the rogue makes short work of the necromancer. Pieces of the puzzle rotated, tactical superiority achieved.
This is why its great to have powers that attack different defenses. And this is also why barging in without any foreknowledge works: if someone in the party happens to have a frost weapon, and they happen to be fighting fire elementals, great – they have an upper hand. They still have to maneuver themselves into position to leverage it. This is also why entirely random magic items would have been a good idea, if most of them weren’t so terrible, but I digress.
Preparation is everything
Things change when players know what they’ll be facing. Wizards get to enjoy their ability to swap around prepared powers at the start of the day. Everyone else has to rely on items to change anything about their capabilities. It’s likely that the party has accumulated some “floating” magic items that no one is using, but still don’t melt them down into residium on an off-chance they’ll come in useful. Then there are various consumables.
Items can be broken down into two rough categories: energy (both resistance and damage), and general tactical advantage. All those “push one extra square”, “teleport one square further”, “also prone” effects. The latter category, as their name suggests, are generally useful. It’s possible the party gets lots of extra-push consumables because they know they’ll be fighting on a cliff, for instance, but most of the time these are too generic to be an important part of any actual tactic.
As for resistances and damage types… They’re terrible if the party is prepared. Everyone gains the ability to exploit enemies’ weaknesses. Everyone negates their strengths. And that’s not all. Just like everything else, monster damage is highly formulaic in 4e. Any monster of a given level and role does the same average amount of damage, with minor variability. But they do so in different ways. A brute or a lurker typically deals all its damage in one big hit, whereas controllers tend to rely on area attacks, zones, auras and the like. Skirmishers do multiple attacks. Soldiers punish for violating their marks. Then there’s ongoing damage. And all this adds up, roughly, to same total damage output. Yet resistance applies to them all. Resisting 15 from a 60-damage attack is one thing, resisting 15 from three lots of 20 is wholly different. Some monsters get neutered by resistance, and they’re the ones that are typically trivial to predict. We’re heading into a volcano? Better grab some fire resistance. Necromancer threatens the village? Here’s my trusty cryptspawn potion. The situation with vulnerabilities to some damage type is similar: if everyone suddenly deals +10 damage to a monster on each attack, the monster goes *pop* very quickly.
What’s my problem?
With monsters going *pop* quickly, that is. None, as long as I have control over the difficulty of an encounter. But these preparations have the potential to turn your set-piece encounter into a cake-walk, and they’re not even that interesting or impressive. You brought a potion of fire resistance to a fight with a red dragon, big woop. You were going to defeat it anyway, now you’ll wipe the floor with it. An element of an encounter was made boring.
Obviously, this is only a problem if the party cares for such preparations. If they keep knocking down doors, they’re playing 4e as intended, as sad as that is. But doing at least some preparations some of the time for the fight ahead is natural. And that’s the thing: trivial preparations are destructive, while involved ones are non-existent. What’s a DM to do? There are a few options.
This means war
This post on Combat as Sport vs Combat as War mxyzplk pointed out in a comment to my previous post describes the important distinction in approaches to combat. 4e is based on Combat as Sport, on a fair fight, on knocking down doors and facing whatever’s there with whatever you have. When the PCs prepare for a fight, they declare War. So give them war.
Increase overall level of encounters by 2 or 3, to account for their preparations. Up the damage of some abilities, introduce auras or environmental effects that make resistance to that energy type almost necessary to win. Of course, this means that the party would be screwed if they tried to fight without any preparations… So telegraph it! Ask if they’re absolutely sure they want to go into a necropolis without any necrotic resistance. This way, the difficulty of an encounter is not actually increased, instead a threat is added that will never be fulfilled. Smoke and mirrors.
Incidentally, don’t let your players fall victim to analysis paralysis at the preparation stage, or they can spend hours debating merits of item A over ritual B. Allow them some leeway in what they’re bringing along, within reason. If they’re going into a volcano, potions of fire resistance are obvious. But mithral ropes are also not out of the question, which the players can bring up when they actually need them. Assume the characters are competent and didn’t forget about necessities, even if players did.
But don’t just negate the party’s preparations by increasing all typed damage by the same amount. If you know the PCs will have resistance or typed damage, modify your monsters around it. It is no longer an interesting piece of the tactical puzzle, so change the game. Have minions drain the resistance for a round on a successful attack. Have environment react in a volatile manner to people using certain type of damage. Give key monster’s powers’ alternative effects on targets with resistance – see wizard powers from Heroes of Shadow for inspiration. Don’t be afraid to give monsters “unfair” abilities if their “fair” abilities no longer do the trick. This goes for over-optimized parties in general.
From the other side of the barricades
If your players want to do scouting and research, study their enemies and learn their weaknesses – great. Give them tools to act on it. Consider allowing all classes, not just wizards, to pick their powers after each extended rest. Knowing what they’ll be facing suddenly becomes relevant. If they learned some specific weakness their foe has, give them an encounter power that anyone can use to signify that, its effect ranging from gaining combat advantage as a free action (Bork the orc enforcer has had a weak knee ever since he took an arrow in it), to negating all the fancy abilities of a target forcing it to rely on basic attacks, save ends (“By your name I bind thee, Azgathog”). This is an example of interactions between characters and monsters which I’ve discussed at length here.
And finally, remember it’s perfectly fine to have your players steamroll an encounter every now and then, just as long as it’s not the boss encounter. Don’t be caught off-guard by innocuous potions of resistance or whetstones of thunder damage. Let the players enjoy their preparations without ruining their own game.