As above. The hobgoblins aren't the same as a zombies.
Monsters with class levels would be like a zombie ranger. Or a wolf barbarian.
Also, tactics and how optimized a party is makes a difference. A party of 4 wizards could die to a couple dogs, because they have low hit points. A party of fighters could die the same, if they all tried to trip and didn't deal damage.
So post what four PCs you had and what the hobgoblins were like, unless you didn't change them, and what zombie stat block were the zombies. I'm guessing in this info is where you'll find out why one did better.
Also, tactics and how optimized a party is makes a difference. A party of 4 wizards could die to a couple dogs, because they have low hit points.
As four trollhounds brought me from full HP at level 6 to dead in one round just last night, i can attest to this.
If you look at the same monsters with the same CR rating number between 3.5 OGL and PFRPG, you'll see that the PFRPG monsters are tougher. That's because PFRPG PCs are more powerful than their 3.5 equivalents, so the monsters needed to be beefed up as well.
The general rule of thumb is that the CR of an NPC is its character level -1. Unless that NPC is of an NPC class (warrior, expert, aristocrat, etc), where the CR is character level -2.
Monsters without racial hit dice instead have class levels. (e.g. goblins, orcs, elves, kobolds). In the Bestiary, they are usually presented as 1st-level warriors, which are usually CR 1/3. The hobgoblin is an exception: it's presented as a 1st-level fighter (CR 1/2).
If you want to make an NPC monster from a 0-HD race, you just make an NPC and apply the monster's racial ability adjustments.
The rule for adding class levels is mostly there when you're advancing a monster that has racial hit dice. (e.g. bugbears, demons, etc.) For example, in my game last night, the PCs encountered an advanced dretch barbarian. I took the basic dretch stats from the bestiary, and added three levels of barbarian. That made it a CR 5 monster with 45 hp (5 HD: 2d8+3d12+15).
After you've finished advancing a monster, go back and check its stats against the Monster Statistics by CR table, to make sure it's in the ballpark. Either tweak the monster's CR or its abilities to get it into the right range.
Monster creation is more of an art than a science, honestly.
No. A Hobgoblin is a 1-hit-die humanoid. As such, it does not have a racial hit-die/level to add to. The one character level is all it has, so it is just like a level-1 NPC, which would be CR 1/2.Shouldn't Hobgoblin be a CR 1 creature in this book? (1/2 + 1 class level)
.
But if you compare it with a Gnoll, which is supposed to be tougher (CR 1), the only thing the Gnoll is better at is dealing damage. That can't be right surely.
Brf: I think you meant 0-HD humanoid. Hobgoblins do not have racial hit dice and gain all of their hit dice through class levels.
Gnolls, on the other hand, DO have racial hit dice, so you would advance a gnoll the same way you'd advance the dretch I mentioned above. PC class levels are generally superior to racial hit dice, in any event.
The example gnoll and hobgoblin are roughly equivalent. They're both in the ballpark when you look at the table I mentioned-- the hobgoblin is on the high side of CR 1/2, and the gnoll on the weak side of CR 1.
That's pretty much true for any adjacent CRs: specific example creatures' general level of ability will sometimes overlap. Again, monster creation is more art than science.
No. A Hobgoblin is a 1-hit-die humanoid. As such, it does not have a racial hit-die/level to add to. The one character level is all it has, so it is just like a level-1 NPC, which would be CR 1/2.Shouldn't Hobgoblin be a CR 1 creature in this book? (1/2 + 1 class level)
.
But if you compare it with a Gnoll, which is supposed to be tougher (CR 1), the only thing the Gnoll is better at is dealing damage. That can't be right surely.
It is pretty trivial to cherry-pick two monsters out of the bestiary that don't make sense when compared to each other. CR is not that finely-tuned. If you feel that the encounter in question represents a greater or lesser threat than its CR indicates, change the CR.
Also, another question along the same lines...
A group of 4 hobgoblins = 4 x 200 XP = 800 xp = CR 3 encounter
But Tables 12-3 (pg 398, core rules) says that 4 monsters = CR+4
1/2 > 1 > 2 > 3 > 4 = CR4 encounter
Which one is correct? Based on the slaughter-fest of my mock combat I would say CR4 is correct.
Generally speaking, when dealing with CR 1 or higher monsters the first time you double (going from 1 to 2) you are now at CR x+2 and the experience tables back that up. Two CR 1's = 800 xp or CR 3. Two CR 2's = 1200 xp or CR 4. And so on.
It is a little wonky when you fall below CR 1. But going by the xp table, 4x CR 1/2 = CR 3 (800 xp). So I would say that 4 hobgoblins = CR 3 encounter. That said, if the heroes were level 1 (APL 1) then this is a CR+2 "hard" encounter. Also, depending on the scenario (the hobgoblins got the jump on the heroes) then that might warrant a further CR+1 factor, especially at level 1. It doesn't take a whole lot to down level 1 PCs.
Some of that is just supposition on my part, so it may be in error.
I think Gnolls should be a 0-HD humanoid, really. There's racial stats for a 0-HD Gnoll in the Advanced Race guide. If I were running a campaign with gnolls, I think I would rebuild them using those stats, and making base gnolls level 2 warriors, or something like that.