Monster Level Equivalency Theory (3.5e Other)

Why a theory?
When you read through a Monster Manual, look at the HD of creatures and then look at their CR. Do you see a trend? No? Well, there isn't one really. This is because different HDs carry different 'value' in terms of monsters. Some (like dragon and outsider) are epic-win, and others (like undead) are epic-fail, and to counteract this problem, the designers of the game just gave more of a lower-value HD to a creature to get its CR to where they felt it should be.

This theory is used in the designing of creatures. Any creatures designed using this theory work with the system. Certain rules are restrictions on what you may do in creation. Other material already created that does not follow this theory will still work. so where you read "No level adjustment" in the racial part, that applies to your race. It does not apply to every race in the game. So if you want to use a Githyanki and some race you created, Githyanki get their level adjustment, but your race would have a racial paragon path of two levels if you wanted to have a race of equivalent strength. It would actually probably have five, so that you can have true paragons.

Fundamental Problems
However, this approach brings with it a pile of fundamental problems.

Abilities Based on HD
Firstly, a lot of abilities (ranging from turning to colour spray) work off HD, rather than CR. This means that these abilities have wacky scaling against many (if not most) monsters, which doesn't really help anyone understand how something works. I literally cannot say either way with any certainty whether something that affects a creature of 4HD is good or not at any level because of this problem. Secondly, DCs for supernatural abilities (about the only sane standard we have in 3.5e for save DC benchmarks) is based on HD, rather than CR. This means that some creatures end up with significantly-higher save DCs than they should. Lastly, and perhaps most importantly, most monsters advance by HD as they gain CR, which means that these problems become worse in advanced monsters as opposed to their 'normal' cousins.

Homebrewed Subsystems
"For characters and most NPCs, their level is equal to their hit dice is equal to their CR. This statement is not true for the majority of monsters. They don't always have levels, and their hit dice often exceeds their CR. While this leads to some odd but manageable behavior in saves and attack bonuses, it is absolutely unworkable with these skill abilities. A creature with humanoid hit dice, for example, gains 1 CR for every 4 hit dice that it possesses. This means that a CR 1 humanoid has 4 hit dice and up to 7 ranks in and "class" skills. It would have access to the skill abilities of a 4th level character if there weren't additional rules governing their access for monsters. And that problem just gets worse as they scale up. A CR 4 humanoid has 16 hit dice, up to 19 ranks in any "class" skills, and the same skill abilities as a 16th level character. This is pretty much unworkable."

- TarkisFlux, regarding skill abilities in the Tome of Prowess

When monsters have Hit Dice that don't equate to their challenge rating and your new subsystem dependent upon hit dice (like any modification of skills to make them useful) you will give a substantial power boost to monsters. Since they are meant to be a challenge for a party of a certain level, increasing their strength disproportionately may increase challenge rating for these kinds of creatures. You should be aware of these things, and write rules to limit these boosts appropriately.

Masking Type Flaws
Some types just suck. For example, would you ever want to take a hit die of animal or humanoid? Just like most people avoid taking levels in commoner, most people avoid gaining hit dice in these types. Other types are extraordinarily powerful. For example, the Outsider type. There is a reason there are not many LA0 Outsiders.

To fix this, there has been work to get types to be balanced with each other. For example, the Variant Giant type is useful for people wanting to make MLET monsters of the Giant type.

Level Adjustment
Wizards of the Coast are on record as stating that they want to make monster player characters weaker than normal player races (see Savage Species). With level adjustment, and monster races, it is hard to have level appropriate abilities, either because the race gives abilities that aren't level appropriate, or the level adjustment slows your progression in classes of rogue and wizard level.

Name of Solution
All of these are not good to leave in, and thus, some alternative approach is needed. Our alternative approach is called the Monster Level Equivalency Theory, or MLET for short (pronounced 'emm-let' or 'omelet' if you're so inclined).

The theory itself
Summary::All monsters should have HD equal to their CR. Without exception. Ever. Creatures need increasing hit point bonuses in the form of constitution boosts or toughness style feats to keep up with damage scaling, but this just mimics how players pick up attribute boosters along the way and generally functions in exactly the same way.

Subtheory (Races)
Races without level adjustment should, without doubt, be considered a challenge rating of 1/2 before applying any class to them. If you have abilities that would make it CR 1 or higher, those should go in a racial paragon path of any length you want. It is when a class of appropriate strength is added that they become CR 1 with their first hit die. Level adjustment doesn't exist.

Projects Using MLET

 * Complete Sublime for an extension of Tome of Battle.
 * Liber Demonica for a rework of everything demonic.
 * Big Book of Monsters for a rebuilding of the monster manual.

With Balance Points
Most monsters created under this system could be fought as a legitimate challenge by anything of the Rogue balance point or higher. Sometimes beings of the Fighter balance point or lower would win, but it is rare. As such, it follows the Same Game Test on the reverse side of the coin. Playing under Tome, these monsters fit in just nicely.