Size/difficulty of encountrs for lvl 10+ in D&D 3.5

Question

Right, so some basics. Homebrew campaign with 6 party members (stared with three and kept growing). Party is Lvl 12.

First character is: Fighter 9/Barbarian 1/Bear Warrior 2.Armor and sword enchanted to all hell (basically every penny he hasn't spent on potions) Sells everything to get more enchants. Has Robilands Gamble and Karmic Strike.

Second Character: Barbarian 10/Peregrine Runner 2. Low AC but puts everything he has into his two swords. Avg dmg per swing is 30+. Kills every thing in sight.

Third Character: Ultimate Monk build (He didn't know anything about D&D and looked up classes. Found it before I did and by the time I knew about it he was too far in to stop him.) Can do upwards of 100+ DMG as it's meant to.

These are my, so called, problem children. The rest are a standard Monk, Wu-Gen (Fire) and a Rogue turned Shadow Thief (homebrew class because Rogue prestige classes suck wihotu lvls in magic user). The problem comes in because we are in a city-based campaign, tracking down a black market ring. So not a lot of monsters there unless they get into like the exotic animal pens or something. So, tossing everything the DMG has at them with hoards of randomly generated NPC enemies. I don't know enough about being a DM to do this effectively so I'm coming to you guys. If I throw out similarly-leveled NPC's they cut right through them as if they were paper. If I throw out high-level NPC's they gang up on them, take a little more damage but still kill everything in their path. I've even tried pitting them against upwards of 20+ low-end enemies at once, but that just prolongs the battle. Nothing can get through the tanks AC except spellcasters. Spellcasters are quickly dispatched first by the pair of high-speed monks, the Wu-Gen magic, or the Rogue's enchated bow. Tank and Barbarian cut a swath through hoards of foes.

Sure, they're having fun because they feel like gods. But they're getting tired of the hoards of weak enemies. The only thing to ever kill a party member was a Lv 15 Assassin they didn't know about. Invisible, with a heavily enchanted scythe. Got a lucky sneak attack in on a old teammate. Critical and nearly max damage on all rolls instakill from nearly full health. Ragequit. Next closest was the Tank taking 4 spells to the chest as he told a ringleader to, "Go suck off his manservant to feel better about his men getting wiped out." Not eloquent but enough to piss off a man on his high horse.

I don't know what to do anymore. If I super spec out enemies with high-end magic equipment so they can mange to hurt anyone in the party, they just take it, pawn it or use it, and get stronger. If I use high-level opponents, they kill it, get mad EXP and get stronger faster. What am I doing wrong here?

tl;dr Party too strong, can't be slowed down. Combat is tedious because too easy. What do?

Edit for additional info:

Looking for NPC designs. In military structure think in terms of Sergeants and Warrant Officers. Race-Class build stuff with minions. Equipping them as you feel necessary. Party is up against a magic-heavy gang. Enchantments and buffs are not out of the question. Standard DMG build won't work for anything not a grunt. Anything 3.5 is cannon. I'm not looking to kill the party, or anyone in particular. But putting a dent in their ego and winning streak would be lovely. They might be new to D&D but they're big gamers. Anything obviously stronger than the rest will get targeted and gangbanged, tanks will relegate lower party members to crowd control. They understand strategy, but not necessarily game mechanics. I'll take whatever you have.

I'm not looking to have the forum do my work for me. But being pointed in the right direction for what I could use against the party would be a big help.

Answer 1

My current campaign also has six players, some of which are similarly powerful (the party Rogue/Shadowdancer/Swordsage can cap out at 200 damage per turn if she can land all six sneak attacks). But I can challenge them. Lets take a look at each party member and a few ways to fight them:

Fighter 9/Barbarian 1/Bear Warrior 2.

First of all - you said his sword is enchanted like crazy. That's great, because it means he's not using the main feature of Bear Warrior (the bear transform). If he turns into a bear, the sword is useless.

Secondly - if he put all of his money into his sword and armor, how much did he spend on other stuff? Specifically save boosters, a means to fly, and a means to see invisible creatures? Because without those, he's a great target for compulsion spells thanks to three classes with poor Will saves (Insanity and Dominate Person are obvious choices, as are Illusion spells), someone with Greater Invisibility simply beating him into the ground, or any flying spellcaster blasting him to pieces with total impunity.

aka: Spellcasters will destroy this guy six ways from Sunday. Conjurors are particularly fun, since if he actually gets close enough to attack, they just Abrupt Jaunt away. He has no answer for that.

Also effective is to have a Necromancer raise things like Greater Shadows or Spectres. He's only got a 50% chance to hit unless that sword has Ghost Touch, and his armor isn't going to help against draining touch attacks. When you don't have Clerics around, these guys can ruin people's day real fast. Best of all they have no gear for the PCs to win.

Barbarian 10/Peregrine Runner 2

Low AC, eh? Sounds like something that the Rogue PC in my party would obliterate, with Greater Invisibility and her six attacks a turn. That's an awful lot of delicious sneak attack dice.

Also, Druids love things with low AC. You know what happens? They use Summon Natures Ally III to get a Dire Wolf, which just trips the low AC person into the ground. Or, they use Summon Nature's Ally V to get 1d4+1 Dire Wolves, cast Animal Growth to make them all huge size (you can hit all of them with one casting if they're in range), and watch the poor low AC Barbarian try to stand.

Or, use Summon Nature's Ally V to get a Dire Lion, and Animal Growth that. How is your low AC player going to do against a huge monster with five attacks and pounce (and with animal growth, a pretty respectable +25 Grapple)? Once he's grappled by the lion, he can only use a single light weapon, so his own attack ability is seriously diminished.

Go up a couple of levels and use Summon Nature's Ally VII to get 1d4+1 of those Dire Lions. I really doubt he can take four of them when they're all under Animal Growth. If you want, there's also lots of elementals on the Druid summoning list with damage reduction and ways to make someone have a bad day.

Best part? That Druid still has their own animal companion free to attack, AND can cast spells or attack themselves once the summons are in play. Druids have lots of other very powerful things they can do while a PC is busy dealing with their summons. (This is pretty easy to do if the Druid can get the drop on the party, since they can start summoning while invisible and outside of combat, and the party likely doesn't realize it's happening until the summons appear.)

Ultimate Monk build

I'm not all that familiar with this build, honestly. Never had to try and counter one specifically. But the above advice stands if he can't see invisible and can't fly.

The build's saves are pretty good, but you can make him make a lot of them. A Cleric with Divine Metamagic and the Twin Spell feat can do some really mean things like cast Twin Destruction. That forces your Monk to make a save or die, twice. If he makes both of them, he still takes 20d6 damage. A little bit of Turn Undead stacking and the Cleric can do this two turns in a row with minimal gear.

A Wizard could simply damage him into the ground with spells like Orb of Acid with Metamagic applied, particularly if he has a way to quicken a second one. The Mailman build is an example of this type of setup. With Empower and Maximize applied that's up to 135 damage with no save to avoid any of it, and the Monk has to make a save to avoid the secondary effect. Monk gets into range to counterattack? Abrupt Jaunt, or Contingency.

They Probably Won't Like It

The problem with what I just described is that most of those tend to not be a lot of fun if you're on the receiving end. Insanity can be pretty funny depending on how the dice go, but starting a combat and having two save or dies or 200 damage simply thrown at you can turn pretty not fun, especially if it's overused. Similarly, being locked down by four huge summons chain tripping/grappling can be pretty sucky, especially if you try to get out of it only to find the Druid waiting to drop something nastier on you. A party consisting of a well prepared Wizard, Cleric, and Druid (or any combination of the tier 1 spellcasters, really) getting the ambush on the party will almost certainly result in dead party members.

The party should be defeating a typical encounter, so you have to be careful busting out the proverbial rocket launcher. It might be safer to use your own high damage dealing melee NPCs, to make a fight where the party feels threatened but isn't quite as lethal.

Ultimately, spellcasters will beat melee users at this level. That's how the game goes. So if you want to beat them, the general direction you should be going is using spellcasters who can avoid being attacked while dishing out lethal spells. A melee heavy party doesn't have a lot of effective ways to fight a couple of powerful Wizards.

Avoiding Making the Party Stronger

Another problem you're having is that sending out gear so NPCs can challenge the party results in the party having more gear. In a case like this, you can use classes that don't need as much gear, or use monsters that aren't carrying treasure at all.

If the party is causing problems for people locally, a powerful spellcaster could respond by polymorphing henchmen into powerful monsters. Those don't require gear but still fit within the story.

You can also go ahead and bring out the big guns, killing off one or two party members. The money they'll have to spend on resurrections (or gearing up a new PC) will act as a limiting factor.

Ignore CR

CR is just a tool to try and estimate encounter difficulty, and it doesn't always do the job very well. If following the CR is making encounters too easy, you'll have to set it aside and tune the encounters as needed for your campaign. Your PCs already have an edge in that there's six of them, whereas the CR is built around a party of four.

Answer 2

Unfortunately, CR is a rough estimate. As a general rule of thumb, you need to build your NPCs to be as optimised as the party, which is a couple of orders more optimised than what's found as a default NPC from the DMG. Anticipate spending a few hours per NPC per round you expect them to survive.

Use this handbook index to build each of your NPCs. Anticipate that they'll get one shot off. (That some get more than one off is representative of the relatively low optimisation of your party.) Remember that "buying" magical items is constrained by city size; at these levels there should be nothing that most cities can afford to sell them. Unfortunately, the side that acts first almost always wins at mid-to-high level 3.5. They should fear spellcasters. They should fear craft contingent spell. They should fear builds designed to be effective. Consider the story of the lawn chair.

You will especially want to read:

• The Dungeon Master's Handbook
• Challenging D&D 3.5 and Pathfinder Parties in Practice

Even more unfortunately, it sounds like you're using the wrong game system. "The problem comes in because we are in a city-based campaign, tracking down a black market ring." is not a problem designed for high level 3.5 play, not least because a competent spellcaster could solve it in an afternoon. Consider other game systems (worth its own system-recommendation question) that fit your game's needs more ably.

For a dent in their winning streak looking at the low-level build handbook. my personal taste is to the anima gish, but that's because I do love the binder. For a lieutenant for them to face, look at the one man army, this guy (and his minions) are not someone they want to fight in a fair fight.