Under what circumstances might a character want to level up in RHD?

[Malimar]

So I was considering making an explicit proclamation that, despite whatever the rules say, you are permitted in my game to take levels in your RHD if you so choose.

(I'm not talking about leveling up in a monster class a la Savage Species. I'm talking about taking RHD on top of the base required for your race.)

But then I realized, why would anybody ever want to do that? Outsider and Dragon RHD might be tier 5 or so on the basis of having (well, being) good chassis, but that just goes to show how terrible tier 5 and 6 classes are, not a real reason to take them.

The only reason I can think of is if you're a monster that advances through HD and you want to get a size increase from that. But I can't think of any monsters for whom sufficient RHD would be worth the size increase compared to class levels. Or maybe there are monsters who have good SLAs whose caster level are based on RHD, though I can't think of any of those, either.

So I ask the Playground, out of curiosity: what weird and unusual optimization shenanigans might you be able to pull off by having the option to level up in RHD?

[ATHATH]

Aren't there some feats (and other things) that have their effects dependent on your RHD? IIRC, the Stamp feat is one of them.

[flappeercraft]

The only way I can think of being a god reason for having RHD is if you have a quick way to get RHD and you already have 9ths. For example acquiring 10 lycanthropy strands would be a rather quick process and worth it if you have no reason to take any more levels. That or for a beatstick.

[Buufreak]

I personally would take them if it was something like dragon or outsider and had 1 to 1 wizard progression. That's a big if, though, and rather theoretical and not something currently in print.

[ShurikVch]

Feral template - from Savage Species - gives SAs/SQs based on racial HD, and, since it's Monstrous Humanoid HD, it's not so bad for melee specialist

Ogre Mage template - from Warcraft the RPG - gives spellcasting for racial HD

[Nifft]

In a low-tier game, Dragon and Outsider HD are pretty competitive against low-tier classes.

In a high-tier Gestalt game, Dragon and Outsider HD can cover the non-caster defenses reasonably well for a while.

[Dimers]

The only reason I can think of is if you're a monster that advances through HD and you want to get a size increase from that. But I can't think of any monsters for whom sufficient RHD would be worth the size increase compared to class levels.

Funny you should ask. I just made a were-dire-badger, which is Medium at the minimum 3HD but gets Large if you add a single HD more. So, +8 Strength, +4 Con, -2 Dex, +2 natural armor, +5' reach as a single level's benefits? Sure, I'll take that. (Yes, I know, you have to factor in the LA and other three RHD, but if you're going that route anyway ...)

[Celestia]

Well, there are a couple creatures that can get a size increase with only one or two extra RHD, and that might be worth the investment. Probably not worth it, though, if you have to spend more than that.

It might also be a not bad idea if you are playing a dragon, and advancing RHD also advances your age category. That can get you some extra things. It's still worse than most classes, of course, but in a low optimization game, you're probably going to have no problem contributing.

I can't think of any other instances where it would be worthwhile.

[Esprit15]

Advancing RHD for the savage species trumpet archon also allows it to advance its cleric level. I’ll leave the debate about whether it continues to gain BAB and saves until 20 HD for another thread.

[Anthrowhale]

Sylph (Outsider, MMII, LA+5, 7th level casting on 3RHD)
Spell Weaver (Monstrous Humanoid, MMII, LA+7, 12th level casting on 10RHD)
Phaerimm (Aberration, LEoF, LA+2, 1st level casting on 1 RHD)

... all advance sorcerer casting with RHD.

[Telonius]

There are a few Special Abilities that have saves keyed specifically to Racial HDs: Ability Drain, Breath Weapon, some Fear effects, and Poison.

There are probably a few niche cases where a melee build would need Full BAB, good saves, and a bunch of skills to qualify for something; Dragon or Outsider hit dice could be useful there.

[Malimar]

Interesting answers! Mostly (but not completely) roughly along the lines of what I expected, but it's always nice to have specifics.

It's been pointed out that (http://www.giantitp.com/forums/showsinglepost.php?p=22573367&postcount=758) Wyvern ups to Huge with application of 1RHD, Gargantuan with 3 more (and they're Dragon RHD, which are one of the two decent ones). That's probably among the most bang-for-your-buck monsters as RHD-for-size-increase goes. Just gotta persuade your DM to assign 'em an LA you'll need to eat along with the wyvern's base 7RHD.