Can I give a creature class levels when it increases in HD?

[Akisu]

Hello all!

I am currently playing in a Carrion Crown campaign, and GM allowed me to play a version of the Dread Necromancer from DnD 3.5 updated for Pathfinder.
Now from this class I can gain a trusty undead guardian, who gains HDs as I gain levels. The ability reads as follows:

Quote:

Undead Guardian:

The Dread Necromancer obtains an undead minion (a human warrior skeleton or human warrior zombie) that serves her. Obtaining the guardian involves a 24-hour ritual and 100gp worth of materials.
At first, the guardian is completely typical, but it gains power as the Dread Necromancer gains levels. The guardian has a number of Hit Dice equal to the necromancer’s HD. It also receives a bonus to its natural armor equal to one-half the Dread Necromancer’s HD, and a bonus equal to one-third of the Dread Necromancer’s class level to its Strength and Dexterity scores.
The Undead Guardian has an Intelligence score equal to (5 + 1/2 its master's HD).

So my question is (and why I posted this in rules questions instead of homebrew), since it gains HD equal to my HD, would it be able to choose class levels instead of racial HD?

I also know that the text reads warrior skeleton and warrior zombie. I'm guessing it's a typo from old 3.5 (as those had warrior levels) and in Pathfinder it would probaly start out with a racial HD instead.

[Melkiador]

By default, it would only gain racial hit dice, which is a lot closer to gaining an NPC class like warrior than a PC class like fighter. You could always ask your GM for it anyway, but I’d expect a negative answer.

[Azothath]

If it were PF1 material...
Dread Necromancer 3.5 Summon Familiar: At 7th level or anytime thereafter, a dread necromancer can obtain a familiar. The familiar she acquires is more powerful than a standard wizard's or sorcerer's familiar, but it is unequivocally evil. The player of a dread necromancer character chooses one of the following creatures: imp (devil), quasit (demon), vargouille, or ghostly visage. All these creatures are described in the Monster Manual except for the ghostly visage, an undead symbiont described on page 221 of the Fiend Folio.
A dread necromancer's familiar gains the usual familiar benefits given on pages 52—53 of the Player's Handbook, with two exceptions. Its type does not change, and it does not gain the exceptional ability to speak with other creatures of its kind. A dread necromancer's familiar can use its ability to deliver touch spells such as its master's charnel touch, scabrous touch, or enervating touch attack. The master must use a standard action to imbue the touch attack into her familiar.

as there's no Skeletal Warrior...(d20PFSRD lists it as a template)
PF1 Skeletal Champion monster and one might assume all simple, martial weapons, lgt, med, & hvy armor, lt & hvy shields but ask. Likely you'll want a greatsword, earthbreaker, or weapon with reach, and a comp longbow....
PF1 Skeletal Champion template
if you can get a juju zombie... but tell him about Soulbound Doll. It's an standard improved familiar and pretty good just try to get more weapon proficiencies than a dagger.

If it is similar to a PF1 Familiar, which governs how it progresses...

So if a 11th level wizard has a skunk familiar, Wiz HP=42 means 11HD skunk familiar has HP=21. No class levels but 11 skill points & maybe Familiar's class skills (Acrobatics, Climb, Fly, Perception, Stealth, and Swim) and Familiar's get to use the Master's ranks in skills. Read the Familiar link above.

[Melkiador]

Human warrior skeleton is just a fairly basic skeleton in 3.5. Pathfinder Skeletons are similar but different. The direct parallel is the regular “human skeleton” in Pathfinder, but it carries clear version differences.

https://www.d20srd.org/srd/monsters/skeleton.htm

The human warrior zombie doesn’t seem to be a default zombie in 3.5.

But again, this is based off a warrior, which is an NPC class. It’s not a fighter which is a PC class

[Mysterious Stranger]

Since you are using a homebrew class the rules forum is not the correct form for this and should be posted in the homebrew forum. 3.5 is not Pathfinder so anything from that updated to Pathfinder is by definition a homebrew class.

That being the case look at the template your GM is giving the undead minion. Unless the template is the skeletal champion it cannot have class levels. The skeletal template specifies that that the undead cannot have class levels. That is what the skeletal champion template is for.

[Melkiador]

3.5 isn’t really homebrew. It’s more like 0th party. But the homebrew board is probably the closest thing to a place to support that.

[Akisu]

Melkiador wrote:

By default, it would only gain racial hit dice, which is a lot closer to gaining an NPC class like warrior than a PC class like fighter. You could always ask your GM for it anyway, but I’d expect a negative answer.

Thanks for the reply. As it is, I can't find any rules that would prevent me from choosing class or NPC class levels, but I get that the default is racial HD. I've talked with GM and he sees it like this as well.

[Akisu]

Mysterious Stranger wrote:

Since you are using a homebrew class the rules forum is not the correct form for this and should be posted in the homebrew forum. 3.5 is not Pathfinder so anything from that updated to Pathfinder is by definition a homebrew class.

That being the case look at the template your GM is giving the undead minion. Unless the template is the skeletal champion it cannot have class levels. The skeletal template specifies that that the undead cannot have class levels. That is what the skeletal champion template is for.

I know the rules of that class itself is homebrew/3rd party, but my question should fall under the rules question board since it would apply in any other instances of monsters gaining HD as well.

[Azothath]

Azothath wrote:

If it were PF1 material...

...
If it is similar to a PF1 Familiar, which governs how it progresses...

again, the above are the rules you'll use in PF1.

I'm assuming you'll change the familiar base to the creature your GM designates.

A Faerie Dragon is the similar example that will meet your needs for what effects are related to HD.
As the Faerie Dragon increases the effects related to HD, its caster level increases and the DCs for its saves go up. It doesn't progress with more spells (even though it's a dragon as there's no chart for it). It does not gain its own BAB or Save increases as those are outlined in the familiar description. AFAIK it doesn't gain feats & skill points as "effects related to HD" is usually translated as the familiars existing abilities. The pitiful number of skill points some GMs allow via GM Caveat. Otherwise the Familiar only gains what's on the familiar table. It gains the Master's poor BAB, poor saves, half the poor HPs, but gains shared skill ranks. The familiar becomes worse as level increases as it falls behind the higher CRs the Master experiences with higher APL.
Faerie Dragons can use wands (Sor spell list) so they're a big help in that dept. Your skeleton can wield a weapon...

In your example, the Familiar is easy and cheap to replace. That is certainly an advantage given the usual hassle it is. By 7th level your familiar is just gonna be a one-hit speed bump. They are helpful for information gathering but yours won't be in general unless you disguise it.
My ADVICE is to get a bonded object if you can. Use Blood Sentinel:T3 to create a temporary familiar when it's needed. Animate Dead should suffice for extra mooks.

When I played a similar class my undead familiar was a ghoul. It was a bit of a hassle as it wanted to eat fallen party members or NPCs (which, of course, would get us into trouble from other NPCs & townfolk/farmers that saw it. It only nibbled a bit on party members before I stopped it but luckily Raise Dead recovers small missing pieces...).

[Mysterious Stranger]

The undead companion of the Dread Necromancer is a class feature of the class. Anytime in Pathfinder a creature is gained as a class feature how it advances is spelled out in the description of that class feature. In many cases they simply use the description from another class, but how the creature advances is always explicitly spelled out. There are rules for advancing a creature by adding class levels, but those do not apply to creatures gained as class features. This situation will not ever come up on any official class.

[Akisu]

Good answer, thanks.
You're right that official classes typically follow their own progression, like animal companions, or they refer to the Leadership feat.
Namely leadership and the monstrous companion feat, they specifically mentions levels or class levels instead of HDs, which is quite telling.
Link to those are here:
Leadership
Monstrous companion

[Mysterious Stranger]

The cohort from leadership specifies it can be of any race or class. The cohort is usually from a race that does not have racial HD. Because of that I would not use Leadership as a reference for your question

Monstrous Companion explicitly states the companion can gain class levels. That would indicate it is the exception not the rule. If any companion can gain levels Monstrous Companion would not need to specify it can gain class level.

You are also ignoring the most important thing about my first post. A Skeleton cannot have class levels, that requires the Skeletal Champion template. Unless the GM gave your undead companion the Skeleton template or a custom template RAW it cannot have class levels period.

[Dragonchess Player]

Mysterious Stranger wrote:

The cohort from leadership specifies it can be of any race or class. The cohort is usually from a race that does not have racial HD. Because of that I would not use Leadership as a reference for your question.

I just want to add that Ultimate Intrigue does provide guidelines for monster cohorts (possibly including class levels on top of racial HD, if the PC's leadership score is high enough) with the Leadership feat. There is even a strong suggestion in the Reign of Winter AP for allowing a monster cohort (Greta, the winter wolf)...

However, in relation to the OP, using the Monstrous Companion feat as a guideline for a GM-created feat that converts the dread necromancer's undead minion from a "basic" skeleton using undead HD to a cohort skeleton warrior using (fewer) class levels would probably be OK. Note however, just like regular cohorts, the PC should have to account for the skeleton warrior's equipment and not be able to use the minion bonuses to natural armor; also, the ability scores should be generated as an NPC (again, not using the minion bonuses).

[Name Violation]

If you're already using 3.5, check out Unearthed Arcana, it had a variant familiar for wizard necromancers that replaced the familiar with a skeleton that advanced HD as you leveled