View Full Version : A replacement for CR for low magic...

2010-04-15, 06:16 PM
I've never really understood the CR system, mostly because it seems to have no mechanical ties, though at least it's easier to use than the Threat Rating system used in the old Starwars game.

This is basically my "rule of thumb" for my games in Mecha Victoriana, a setting with somewhat hobbled magic and i've found that it works pretty well and can be adapted to Social and Skill challenges as well. I'd like some help fine tuning it, if that's ok.

Before working out an encounter, you need to know a few things. This system works fine when the party are a reasonable range of BAB values but in situations where everyone has min/maxed, it goes to hell somewhat, to the point where the incompetend may as well not take part.

The Basics:
The first value you need is the individual Combat Potential of each character in the encounter [not necessarily the party].

Each character has a CP equal to their Base Attack Bonus plus any Ęther they may possess. Ęther is a measure of spellcasting power and is at most 2 less than the character's level. I have no idea how to retool that back into core D&D, honest i've tried.

CP = BAB + Ęther + Focuses

From here, one can calculate the Encounter Combat Potential [ECP]. The ECP is equal to the sum of the CP values of those taking part in the encounter.

ECP = Sum of Character CPs

Then finally, you need the Average Combat Potential [ACP], which is the ECP divided by the number of characters.

ACP = ECP ÷ Number of Characters

This last value, the ACP, is the most important, while the ECP is used as a guideline for how much stuff needs to be in the encounter.

Enemy CP:

As one might expect, the CP of all enemies to be used is calculated in much the same way, or if using the MV monster kits the formula is stated on the kit in question [Things, for instance, being more powerful than their BAB would indicate].

Building an Encounter:

Ok, now we have the Average and Encounter CPs, we can begin building an encounter. First, we need to decide on the difficulty of the encounter, as follows:

CP Multiplier:


Skirmish, Easy|

Skirmish, Brutal|

Battle, Life and Death|

Last Stand|

This figure is the Encounter Budget we'll be working with from now on.

If any of the following conditions apply, adjust the Budget as follows:


Enemy has significant Cover Advantage|
-1 per 2 enemies

Players have significant Cover Advantage|
+1 per 2 characters

Enemy has Hard Cover|
-1 per enemy

Characters have Hard Cover|
+1 per Character

Character Movement seriously restricted|
-2 per enemy

Enemy Movement seriously restricted|+2 per Character

Once you have youre budget, you're ready to pick your critters.

Critter CP:
Ok, so we know both our ACP and our Encounter Budget.

In order to build our encounters, we need to know the CP of your antagonists, which is calculated identically to the individual CPs of your characters:

CP = BAB + Ęther + Focuses

From there, you take that CP and compare it to this table (http://mulletmanalive.deviantart.com/art/Monster-CP-Table-160848705), which gives you the Modified CP [MCP] of the enemy. This is based on the fact that enemies get exponentially more dangerous the more able they are than the PCs and so the table adds the square of the difference in ability to the creature's CP if it is stronger. These values have held true in MV and work reasonably well in the couple of tests i did with "Core" classes.

From there, it's just simple addition. The total CP should be equal to your Budget.

For Skill Based Encounters:
Ever wondered how to award challenge and xp for a negotiation that's critical to the story, an evasion from a pack of dogs or for forging that sword before the deadline?

Look no further, at least if you're using this quirky system.

In this case, for opposed checks, simply divide the enemy's skill bonus by 3 and compare them to the table to get the MCP and thus an idea of whether the challenge is enough.

This works fine for situations where the challenge is based on opposed checks in a "to a given total" contest, or where the two characters have to reach a given combined total roll fastest.

If you have a situation where a given number of successes must be scored against a DC before a certain number of failures occurs, then divide the DC by 3. This assumes you must make 3 successes before failing once. For every additional success needed, increase the CP by 1 and for every failure allowed, reduce the CP by 1. Once this is done, it may be compared to the table, as normal.

Incorporating Skill based components into combat encounters is simply a case of treating them as additional monsters, though only if failure would significantly alter the outcome of the combat.

Example: The PCs are pinned down at the end of a corridor blocked by a heavy steel door with a complex set of locks and a trap. An overwhelming number of capable troops [their ACP-2] are approaching down the corridor, firing as they come, making this solidly in the Last Stand category.

This leaves a total of 4 successes against DC 30 to get the door open. Success means that they survive the encounter and have temporarily defeated their foes, failure means that they're trapped, outgunned and pretty much dead.

In this case, the skill component certainly counts towards the encounter.

Counter-Example:The same group of PCs decide to sneak up to a group of guards and silence them. Success or failure on the skill check will only affect the difficulty of the challenge, not necessarily the outcome [the PCs wouldn't be attacking foes they didn't think they could take period] and hence doesn't affect the CP of the encounter.

The Problem:

From here, you guys would have to use the D&D CR costs tables. I don't actually award XP for combat, instead setting objectives that must be accomplished in order to gain chunks of XP. On the other hand, I assume that there should be about 5 x the ECP in an "average" Mission [Adventure] and that there should be 3-5 such missions per character level...take from that what you will.

With my exerience system, an average mission is worth 2000xp per 2 character levels or parts thereof in the party, so that's about 50xp per CP faced, give or take [usually closer to 30]

That aside, I'm actually wondering how this would cope in a min/maxed situation [such practices, beyond not being incompetent, are unwise in my games so we haven't really experienced it] so any input, especially willingness to test it directly, would be much appreciated.