Give lots of your humanoids and giants a reach weapon. Have them use appropriate reach tactics. This will substantially increase their effectiveness and increase the challenge to your party. Your players can counter this by adjusting tactics. Players who use the standard reckless-rush-and-attack bad tactics will find reach weapons especially painful.
I doubt that will be enough for a 6 person party. You'll need to do more than that to make things 50% more difficult.
|Aotrscommander RPG Superstar 2008 Top 32|
And NO SOLO BOSSES. Ever.
There are ways around that, if you are prepared to bend things in the direction of drama/gameplay a bit.
I took inspiration from 4E's solo montser idea and created what I call the Defiant template. Long story short, each application of the template increments the creature's hit points (and it gets maximum hit points) as a seperate block and gives it one reroll on a failed save (at the cost of effectiveley giving itself a negative level). If the creature is exposed to a save-or-suck/die effect/condition, it can expend an entire increment of its hit points to ignore that effect, or at the end of its turn, it can essentially Iron Heart Surge away any effect on it by likewise expending a block of hit points.
This has proven to be wildly effective (I play with 7-8 character party sizes) and is even easy to slap on mid-combat, if you like/need. It increases the creature's defensive abilities to ensure it gets to last long enough to be interesting, and means that it also doesn't totally negate combat-ending abilities entirely (in some respects, it encourages them to be saved for finishers); which is the problem with just raising save DCs and adding hard-counters (of the Final Fantasy Death syndrome, where the only creatures that are effected by it aren't worth using it on).
OP, having done this myself (for even more characters in the end), my solution was to increase the number of monsters generally, but rather than straight +50% (or +100% in my case) to a few less monsters, but with class levels and liberal applications of the aforementioned Defiant template on bosses.
I don't know how much use it would be to you, but I worked out roughly what to add by using a spreadsheet (albeit for 3.5, not PF) to work out the base XP at normal progression (in 3.5) and then worked with the difference between the way I award XP and the increased number of players. Then, essentially, just added stuff until the one minuts t'other was about equal.
I have relevant information/spreadsheets (when we re-start, we're about to head into book 5) if you think that might save you some effort, though probably not a lot, since it's 3.5, not PF and using the original AP, not the PF revised edition. Though it potentially could save you doing it entirely yourself?
In 3.5 rules, I only award half the XP 3.5 normally does, except for boss fights, where I award full.
|Mark Hoover 330|
At lower levels, examine the enemy's choices in weapons. Did you know fey are able to use all Simple weapons? Even in the Simple group, a low level fey might have better results with a crossbow than a dart.
Also armor. A goblin warrior 1 can technically be wearing ANY armor; why is it only donning leather? Throwing hide armor and a shield on an ogre might make the fight a lot longer, depending on the build of the PCs.
NPC Adepts. Adding a couple of these to a fight, having them do nothing but create pockets of Obscuring Mist, healing and buffing their buddies can also pump up the challenge ratings.
Templates are good. Advanced, Fiendish... heck, just turning one or two of the enemies into zombies can work wonders.
The biggest thing that 6 PCs bring with them is half again as many sets of actions. This force multiplier can wreak havoc with a pre-written fight. A CR 5 fight with 2 ogres meant to face off against 4 level 3 PCs for example is a straight-forward melee but, especially in RotRl was designed for a balanced party of 4 PCs starting from a 15 pt buy, with 4 Standard actions, each of which deals a middling amount of damage.
Consider if you have 6 well-optimized characters in that same fight. One is an Arcane blaster type, one is 2/3 BAB ranged attacker, the other 4 are either 2/3 BAB or full BAB melee types. With 6 attacks, at least 4 of which have at least a +9 to hit, and one dealing 4d6 Fire targeting Touch, against 2 ogres... this is basically a foregone conclusion.
Oh, one other thing you could do is to change up terrain. Have the goblins sprinkle minor traps around that deliver Conditions, like a stink-bomb that Sickens for 1 minute hidden in a square; low obstacles that make Difficult Terrain scattered in the map; oil filling some squares with foes waiting to toss Tindertwigs into them, that kind of thing.
If you're not going to add MORE enemies you need to find a way to eat up some of your PCs extra actions in other ways.
Don't forget about terrain and the ways your NPC's can alter it.
Jump on a table +1 for high ground
Throw downs caltrops before your PC's enter a room since there was a large number of them and he NPC's heard them coming
Entangle, Stone Call and Illusionary Terrain.
Use bottle necks like hallways and narrow passages to your advantage and limit the number of PC's that can engage from one direction.
Surprise rounds! (for you of course)
|Zog of Deadwood|
Use those monster special abilities, and ignore the AP whenever it has the monsters acting really dumb. Maybe 4 PCs need a break now and then. 6 PCs do not. If the monsters have Power Attack and are using a one-handed weapon with nothing in their other hand, have them attack two-handed for the extra damage (or give them a tower shield, at least). Give the bad guys guard beasts with scent so they're not as easily surprised (speaking of which, don't forget the increased sensory range of the few dragons in the AP, who should never be surprised by anything short of mass teleport into attack range). If monsters know the party is near, readied actions can prevent the party winning initiative and DPSing them down before they get off a single attack. Don't let the party get away with the 15 minute adventuring day. If they stop to rest too often, let some of the areas they "cleared" become UNcleared. And, by Desna's bright stars, never EVER let them fight a flying dragon or air-walking rune giant on the ground. Those creatures have ranged attacks and reach for a reason.
Yup, and beyond that there is another thread with a very handy guideline:
At level 3+
Take the encounters listed in the AP and do the following:
For each full BAB class increase all mook hitpoints by 50%. Have 3 full BAB people - that's 100% increase. 4? That's 150%.
For each full arcane over one add mooks that = to the APL of the party. Tailor this to the encounter but in general you want extra foes on the battlefield.
For each 3/4 BAB class over 2 you have add 1 to the DC's/Saves of the mooks. This includes all special abilities\poisons\diseases\etc.
Guess they meant "For each full BAB class over one", that would fit to the example and the previous text.
Since more players means they need more overall XP, you can even hand out way more XP per encounter, to compensate the additional challenge. 7 players might simply get 75% more XP, resulting in the same leveling speed as if they would have done as 4 people. In case you don't use milestone leveling anyway.