View Full Version : Challenge Ratings (3.5)

2009-08-06, 06:56 AM
I've been trying to plan and stat out some of the BBEG and challenging encounters. However I'm unsure of what CR should I use for the boss encounters. I know that a CR appropriate encounter should take 20-25% of the party's resources, and doubling the difficulty should increase the CR by 2. By that logic an encounter of appropriate CR+4-6 should nearly take out the entire party. Somewhat logical under the CR system, as a group of PC's is a CR encounter of their level+4. However I haven't really thrown encounters that high above the party's level yet. I wouldn't' want to overdo the encounters and make them too difficult, neither would I would I want to defuse the boss encounters because the PC's can tell after 2 rounds that victory is assured.

I know that when they are actually about to face the boss encounters, I should run a few test runs and I plan on doing that. However simply for now, just to know what kind of CR range I should be aiming for. Share your stories and advice.

13th level party
Scout 3/Ranger 10
Knight 13
Psion(telepath) 13
Cleric 13

So our group isn't that focused on optimization, though I can see the psion going nova in boss encounters. Anyway back to the question? Where in the higher range of CR does it change from PC's probably win, though probably with at least a fatality or two to Overpowering and nearly no chance at all?

Killer Angel
2009-08-06, 07:12 AM
Anyway back to the question? Where in the higher range of CR does it change from PC's probably win, though probably with at least a fatality or two to Overpowering and nearly no chance at all?

The problem is: the CR system is broken; too many monsters have a CR that don't suits their real power. Sometimes the listed CR are too high (easy encounter), sometimes are too low (oppss... TPK).
Not only this: the power of many creatures depends on their immunities and on the ways the group has to overcome them... a swarm can be an easy fight or a terrible thing.
To have some good answer, you should give more details.

2009-08-06, 07:18 AM
There are two basic factors to bear in mind: action economy, and discontinuities.

Action economy means that four characters in a party have a huge advantage over even a tough single enemy because they have four times the actions available.

Discontinuity means that a monster of CR X+2 may not simply be a bit harder than one of CR X but may be designed with the expectation that the PCs have the next higher spell level available to throw at them. Conversely, two CR X monsters may be much less challenging than a CR X+2 encounter should be if that next spell level includes something that trivializes their gimmick.

So, to properly challenge a party with something fair but difficult, I would go with a group of monsters individually close to their level rather than one very tough one or many weaker ones. Or, mix it up a bit and give a tough monster some weak minions to soak up actions. Meanwhile, pay careful attention to special abilities and/or weaknesses and whether the players will simply lack some ability that they're expected to have when facing that kind of monster.

2009-08-06, 07:24 AM
Or, mix it up a bit and give a tough monster some weak minions to soak up actions.

In my experience, this is the way to go.

This, or A LOT of smaller ones with some situational advantage (but is very difficult at higher level).

Another idea is 2, with terrain advantage ad at least 2 good way of move (i.e., teleport, fly, or both).

2009-08-06, 09:56 AM
One thing to avoid in general: Lone medium-sized BBEG who relies on melee. Even if it's an "Overpowering" encounter, the action economy of a 6th-level party can overwhelm a lone CR 11 melee NPC.

A caster would be a different story altogether.

2009-08-06, 10:05 AM
The CR guidelines state "level + 4", so they should have a 50/50 chance vs. a CR 17 creature provided they burn all their resources in the fight. Also, the party seems optimized enough; Swift Hunter isn't bad at all and neither is Cleric. Psion (though Telepathy is among the weaker disciplines) is always decent (especially with Schism) and Knight does the "Controller"-shtick alright.

As long as they aren't picking Weapon Focuses and Toughnesses for their feats, they should be fine. And yeah, a melee BBEG, especially without some free action tricks, is going to get overwhelmed if the party can hit its weak point. A caster can probably hit the party hard enough to make for a fair fight, depending on how much caster mojo you pull out (it'll be fine as long as you don't throw a CR 17 NPC Wizard/Cleric/Druid at them; 9th level spells would just wipe the floor with the party).

2009-08-06, 11:26 AM
I've found (as others mention, above) that CR isn't a great guide, and as well that solo encounters are really lower than their CR indicates (unless the enemy is difficult to reach/affect).

If the party has glaring weak points (a 4th level party in which nobody can fly yet, encountering flying foes with ranged weapons) the CR can indicate an easy win for the party but result in a spectacular loss. Imps and quasits are CR2 flying, invisible foes with fast healing. They can play hit-and run on a low level party with little risk, particularly if they have a ranged attack they can use over and over again (a level of warlock!).

Vice versa, a high CR fight (say, a higher level priest) could be a pushover if played to the party's strengths. The warlock uses her action each round to ready a blast to disrupt casting, bard strips buffs with his dispels, and the big priest gets flanked by the two melee guys, gets pounded on while unable to use SLAs or spells. (Yes, this happened recently). Single high CR foes are particularly vulnerable that way - the party can afford to use their actions for shutdown.

Multiple foes causing AoE saves however can easily be under CRd. Area effect saves that apply every round from multiple foes can make for pretty good chances of party members failing - eventually people roll 1s.

2009-08-06, 03:35 PM
What CR really, truly boils down to is how strong their save DCs (and/or attack routines) are and how many hit points they're allowed to have. Personally, I think a CR is seen at it's best when you're using as many monsters as you have PCs. If you have a CR+4 encounter that is a single creature, you're asking for an extreme; the encounter will end up costing the party a great amount of resources, or the monster gets face-rolled.

With the information you gave us, I would personally suggest a CR+3, and have a plan up your sleeve if the psion novas (if you need to make it CR+4 to include this plan, then do it). Make the BBEG CR15 and mooks add up to CR14 (2 CR12s or 4 CR10s), and you'll have a CR16 encounter. Since I am embarassingly ignorant of psionics, I can't offer any advice concerning that.