I am attempting to create an encounter-table generator to end all encounter-table generators. I am doing this because it seems like an interesting project.

In order to do this, I need to create a data file of all the monsters in the Monster Manual along with their pertinent information. One of the things I want my encounter generator to do is automatically apply advancements and templates on all relevant monsters, so that automatically advanced creatures are present (to varying levels of possibility) etc.

But I come across entries like the Hound Archon. It has two entries on MM page 17, a Hound Archon which advances via additional HD, and a Hound Archon Hero, 11th-Level Paladin which advanced via character class.

Does this mean that the Hound Archon Hero is only ever at least an 11th-Level Paladin, or surely I would come across a 1st-Level Hound Archon Hero? Does this indicate that although it advances via character class, it is only ever a Paladin, never a Cleric for example?

I notice that the base stats for the Hound Archon Hero are higher than the Hound Archon, but they are higher than the additional points an 11th-Level character would have, why is this?

Is it possible that a Hound Archon could advance by HD and then by character class as well?

There are a few other entries like this, Aboleth (page 9, MM), where it's Aboleth Mage is a 10th-Level Wizard that advances via character class. This one seems to me like it is only ever a Wizard due to it being named a Mage, but perhaps any class can be applied to the Aboleth?

Are these multi-entry monsters just indicating to me that they can advance via both HD and character class?

  • \$\begingroup\$ Is the question here, “when can monsters advance by class?” \$\endgroup\$
    – fectin
    Commented Nov 5, 2019 at 21:33

2 Answers 2


You’re looking at DM-facing content. Those entries aren’t rules. They’re suggestions and guidelines to help the DM. The DM can (and should) advance creatures however they like.

The hound archon hero is just an example of a hound archon advanced in a particular way; it’s not a separate monster. Hound archons usually advance by HD, but they don’t have to. There is no reason why the DM cannot throw a hound archon 1st-level paladin, or a hound archon 3rd-level cleric, or a hound archon 3rd-level wizard/2nd-level monk/7th-level enlightened fist if they want to. They just have to figure out the stats for those things, because the only pre-calculated stats made available were for a hound archon 11th-level paladin.

  • \$\begingroup\$ Or advance the hound archon +4 HD, then slap some class levels on top of that. Reducing HD is also an option for scaling back encounters. \$\endgroup\$
    – L.P.
    Commented Nov 5, 2019 at 21:48
  • \$\begingroup\$ @L.P. Eh, advancement via HD or class levels is well-described and well-supported among the rules/guidelines that DMs have, while reducing HD is not suggested at all, and could much more easily cause problems. \$\endgroup\$
    – KRyan
    Commented Nov 5, 2019 at 21:51
  • \$\begingroup\$ @KRyan do you mean to say that any monster in the MM can be improved via class-level? Or would it only make... thematic sense to improve those where an example of improving by class levels is shown, or are otherwise listed as advancing by class? \$\endgroup\$ Commented Nov 5, 2019 at 22:33
  • 1
    \$\begingroup\$ @NeomerArcana The so-called “rule 0” of the game is that the DM can change any rule, and pretty much all DM-facing content is written with that in mind. They’re their to make the DM’s life easier; very, very little of it is intended to significantly restrain the DM. Some of it is stronger than others, but in the case of advancing monsters, there are literally guidelines for how to decide how to handle “unusual” class choices (those guidelines don’t function very well, in my opinion, but that’s besides the point). \$\endgroup\$
    – KRyan
    Commented Nov 5, 2019 at 22:37
  • \$\begingroup\$ Good answer. Probably also important to note, advancing a creature by monster levels adds far less abilities (and therefore difficulty) than advancing by class levels. Monster levels can make a creature harder to kill - advancing by class levels makes them more of a threat to the party, since they have access to the same rules and abilities as the characters. \$\endgroup\$
    – Wyrmwood
    Commented Nov 6, 2019 at 2:04

Monsters which advance by HD can also take class levels if they're intelligent.

The rules on which monsters can advance appear in the D&D 3.5 Monster Manual p.290, "Chapter 4: Improving Monsters". It's actually somewhat ambiguous and noodly.

Creatures can, in general, advance by HD, class levels, or templates. These are not mutually exclusive, and p.290 gives the example of a creature doing all three (a lammasu with the half-dragon template, increasd hit dice, and character levels).

It then states that intelligent, roughly humanoid creatures "most commonly" advance by class level, and will have "By character class" in their advancement line if they fall into this category. All other creatures (non-intelligent, non-humanoidlike, or both) "can" advance by hit dice.

Right away, we have a seeming contradiction. The lammasu isn't humanoid in form, so how can it advance by class level? How can any creature advance by both?

The answer appears to be that even creatures with without "Advancement: By character class" can advance by character level. Page 291 makes this interesting note:

Generally, only monsters with an Advancement entry of "By character class" receive NPC gear; other creatures adding character levels should be treated as monsters of the appropriate CR and assigned treasure, not equipment.

This implies that characters with only HD advancement can be given character levels. This validates things like the aboleth mage, the hypothetical lammasu, the dragons with class levels in Draconomicon, and a hound archon with a class other than paladin. Draconomicon, p.86 also notes that dragons "rarely" adopt character classses, but describes that they occasionally do (despite advancing by hit dice in their description).

Can any creature advance by hit dice? The rules say non-humanoid or non-intelligent creatures "can" do this, but the Hound Archon, advancing by HD, seems to be an example of a creature who explicitly can despite being humanoidlike and intelligent; the troll, meanwhile, also intelligent and humanoid advances by class.

In terms of the actual Humanoid type, I can't think of any example where a human has advanced by raw Humanoid hit dice. Monster Manual p.310 notes that 1HD humanoids always exchange their first HD for that of a character class, and that only humanoids with more than one HD actually use the humanoid tpye; this suggests that actual humanoid-types can't or don't advance by HD.

More specific rules on this appear in Savage Species, although it may be argued that the Monster Manual is the primary source. However, this serves as a useful rule where the Monster Manual is too ambigious. According to Savage Species chapter 9, "Advancing a Monster", monsters must have a minimum of Intelligence 3 to gain class levels. Some monsters advance only by character class.


If we take the advice in both the Monster Manual and Savage Species for advancing a monster, the following applies:

  • Advancing by HD only: Applies to any creature with an Intelligence score below 3, or no Intelligence score. (SS 106) No zombie fighters or cat clerics.
  • Advancing by character level only: Applies to some monsters (SS 105). Those who advance "By character class", which means they are intelligent and reasonably humanoid in shape, most commonly advance by this method. (MM 290)
  • Advancing by both: Creatures which normally advance by HD, but which are intelligent. (MM 291) Numerous precedents exist, including the aboleth mage, the dragon prestige classes of Draconomicon, and the gargoyle rogues in Elder Evils p.152.

Monsters which normally advance by class rarely advance by hit dice, but at least one example is known: the 6HD advanced ogres in Expedition to Castle Ravenloft p.78. It appears that this is not necessarily forbidden, but it raises the problem that there's no listed hit dice limit or size cutoff, meaning that the rules aren't properly prepared for this eventuality.

  • \$\begingroup\$ There are rules prepared, but nobody seems to like the epic level Handbook (with reason) and few seem to know about the original epic rules in the DMG. \$\endgroup\$
    – nijineko
    Commented Nov 6, 2019 at 2:02
  • \$\begingroup\$ @nijineko I'm referring to advancing monsters by monster hit dice here, rather than character levels above 20. \$\endgroup\$ Commented Nov 6, 2019 at 13:44
  • \$\begingroup\$ @QuadraticWizard couldn't you reverse the stats to understand what the Hit Dice is for monsters that don't have HD advancement listed, so that you can then advance them by HD? My understanding is each type has a specific listed HD along with it's bonuses, so you can reverse engineer the HD advancement. (I could be way off) \$\endgroup\$ Commented Nov 6, 2019 at 20:16
  • \$\begingroup\$ @NeomerArcana Yes, but the problem is you won't know what their HD maximum is, or how many HD they can gain before increasing a size class. It could perhaps be argued that e.g. 4 HD and Large size is already the ogre's maximum ("maximum" is not absolute, and can be exceeded in rare occasions, according to Monster Manual p.7, "Advancement"). However, creatures normally advancing by class who have extra HD instead are so rare (I can find only a single instance in 3.5) that a random encounter generator might easily omit this. \$\endgroup\$ Commented Nov 6, 2019 at 22:56
  • \$\begingroup\$ Above 20 HD is also epic.... \$\endgroup\$
    – nijineko
    Commented Nov 6, 2019 at 23:49

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