Any experience with a unified XP/CR/EL system

[quaffeine]

Ahoy!

So I've been thinking about the existing m20 EL mechanic, and wondering if it can be improved. Two shortfalls as I see them are:

• The existing rule counts up all the EL for each successful challenge/encounter, and each PC receives that amount. Maybe it's just an artifact of my time playing D&D, but why would this be the case, rather than dividing the EL amongst the party members? Maybe the math justifies it, but looking at D&D as the alternative, the CR of everything factors into the XP earned, which are then divvied up. I guess I'm looking here for some evidence that using EL in this way is close enough to using XP (which, for better or worse, is a time-proven mechanic that I, at least, am comfortable with from the pace of advancement perspective).
• Additionally, the EL for creatures is their HD, straight. This doesn't account for extraordinary or "boss"-type monsters on one hand. On the other, the adding just 1 EL for each doubling of creatures just makes no sense to me. So if the party is fighting two 16 HD dragons, they get only 17 EL for the encounter?

My goal is to come up with some sort of really elegant little system that could be used to either 1) assign the EL from a set of stats, and/or 2) give some guidelines on designing a creature with a specific EL.

Because I actually do really like the EL mechanic in concept, especially having read through these same things in the 5E DMG, which seems needlessly complicated. So the goal is to create a mechanic where you can easily assign EL to a creature/encounter, and for the PCs to be easily able to track how it gets them to the level at a rate of [10 EL x current level].

All thoughts welcome!

[randalls]

• The existing rule counts up all the EL for each successful challenge/encounter, and each PC receives that amount. Maybe it's just an artifact of my time playing D&D, but why would this be the case, rather than dividing the EL amongst the party members? Maybe the math justifies it, but looking at D&D as the alternative, the CR of everything factors into the XP earned, which are then divvied up. I guess I'm looking here for some evidence that using EL in this way is close enough to using XP (which, for better or worse, is a time-proven mechanic that I, at least, am comfortable with from the pace of advancement perspective).

I've always thought the idea that all characters get all the XP instead of dividing it between them was strange and over-powered. As far as I can recall, however, this is the first time anyone has mentioned it. Since no one else seemed to see anything wrong with this, I just assumed my problem with it was because of my "old school" mind.

- Additionally, the EL for creatures is their HD, straight. This doesn't account for extraordinary or "boss"-type monsters on one hand. On the other, the adding just 1 EL for each doubling of creatures just makes no sense to me. So if the party is fighting two 16 HD dragons, they get only 17 EL for the encounter?

I've never liked the M20 method for calculating ELs. However, I've never been able to come up with a simple better method.

[/quote]My goal is to come up with some sort of really elegant little system that could be used to either 1) assign the EL from a set of stats, and/or 2) give some guidelines on designing a creature with a specific EL.[/quote]

Good luck with that. I'm serious as I believe it would be a nice improvement for M20, I just can't come up with one myself. When I tried a decade or so ago, everything I came up with either was too complex or wasn't a real improvement on the current system.

[quaffeine]

OK, so this has been a minute. But believe it or not I have been ruminating on this, although it took me some time to try to wrap my head around the math for it. And the result I've come up with is actually really interesting. Note: Again, I'm undertaking this exercise in an attempt to put an m20 ruleset together that's compatible with 5E materials. If you don't care about being compatible, then this post is nothing but a fun (?) mathematical proof of sorts.

First, my logic, which I'll try to lay out here in a way that's somewhat sane:

1. CR is a measure of difficulty/danger of a particular challenge (whether creature or other situation, e.g. trap).
2. It also directly (per the 5E DMG) determines the reward PCs get for overcoming it.
3. That reward appears to be increase over time, despite the fact that the actual level of challenge (i.e. "a CR level of X indicates it should be difficult, but not deadly, to a party of four characters of Level X) doesn't.
4. It follows then that the number of CR needed to rise to a particular level would equal the number of XP (again, per the 5E core rulebooks) a PC needed to reach that level versus what was needed for the previous level, i.e. the "delta" between the current and new levels, divided by the number of XP each CR at that particular level represents, multiplied by four.

For example, in 5E, going from level 7 (23,000 XP) to level 8 (34,000 XP) requires a "delta" of 11,000 XP. A CR 7 creature awards a total of 2,900 XP, which works out to 414 XP per CR at level 7. To calculate the number of CR needed to rise from level 7 to 8 in this proposed system:

(XP Level 7 Delta / XP per CR at CR7) * 4, or
(11,000 / 414) * 4 = 108

So using a fun application called a spreadsheet, I calculated the total EL needed to reach each level up to 20, and compared it to the number of CR required for each level using the logic outlined in point #4 above. This is the result:

Though these methods diverge a bit through the upper-middle levels, overall they match up pretty well. Meaning, assuming a couple of other mechanics, you could simply pick up any creature from a 5E source, and award the PCs a number of "EL" equal to the creature's CR, and use the progress as outlined in Purest Essence for advancement (10 EL * current level to reach your next level).

Some of these assumed mechanics, as I see them, are as follows:

1. You're using 5E-style HP progression, otherwise creatures/challenges are bound to get increasingly lethal if PCs only receive 1d6 per level.
2. PCs should have feats or some mechanism that buffs their damage as they progress, otherwise creatures will become increasingly difficult to kill. Now, given that the entire Feats concept is optional in 5E I'm not sure how much water this one holds, but I also haven't heard the results of any campaign that's chosen not to use them in terms of how much deadlier it is or isn't.
3. CR for each and every creatures is awarded to and divided evenly among the PCs. Again, the "add 1 EL for each doubling of enemies" makes absolutely zero sense to me given how much deadlier encounters become when you add enemies. Even less so when I'm trying to make a direct correlation between CR/EL and XP, which traditionally is divided evenly.

All this said, I'm choosing to believe that the accuracy of the line graph above is not just a coincidence of math, and so I'm pretty happy with the concept of using CR interchangeably with EL.

If anyone cares about this topic and also manages to understand the mad ravings above, I'd love some help in looking for faults in this logic.

If it's indeed sound, I'd want to do next is an m20-style distillation of the rules on calculating CR/EL for a creature/challenge given its stats, and vice versa, guidelines for creating a creature/challenge of a particular CR/EL from scratch. This should take into account not just Hit Dice, but attack, defense, and other capabilities as well. But also not require a PhD to use. Again, while the HD = EL standard is probably pretty accurate, it's a little simplistic for my taste. I'd like to more accurately account for things like high damage-output creatures (e.g. "normal" HD/HP but big attacks) and extra-tough creatures ("normal" attacks, but higher HD/HP and or AC).