Guidelines for Creating New Monsters

[Fawsto]

Hello folks!

I was searching for guidelines to build my own creatures when I noticed there is nothing about it in the MM or the DMG. (EDIT: Found something in the DMG, but those guidelines explain things quite poorly).

In reality I was trying a new approach to the Moon Druid where the character has a pool of resources to build a custom battle wildshape. My hope was to even things a bit between lvls 2 and 17, smoothing those power spikes and allowing players a few more choices than Giant Elks and Mammoths without having to trust the flimsy shield of 'changing only the external appearance of the creature'. But stuff like Natural Armor, that seems to be a random number associated with a given creature, for example, makes my head spin. I can't grasp some sort of algorithm to give value to that. Creatures like Polar Bears and Cave Bears make things even weirder, since a Cave Bear has an extra sense (Darkvision) while being otherwise an exact copy of a Polar Bear. That would mean that Darkvision has no value. Like, WTH?

Does someone has a formulae or a graph for that? Something? (I took a while to accept that the HD changes with the SIZE of the Creature). It is a bit confusing, really.

Appreciate the help!

[Ninja_Prawn]

(EDIT: Found something in the DMG, but those guidelines explain things quite poorly)

The DMG guidelines aren't as bad as they look at first glance. Take some time to re-read them. Meditate on them. Use them to reverse-engineer a few MM monsters.

Eventually you will see the light!

[Graelcase]

Angry GM has a good breakdown on the logic and math behind the guidelines and the monsters in the MM. Its the monster building 201 post.

[ZenBear]

In reality I was trying a new approach to the Moon Druid where the character has a pool of resources to build a custom battle wildshape. My hope was to even things a bit between lvls 2 and 17, smoothing those power spikes and allowing players a few more choices than Giant Elks and Mammoths without having to trust the flimsy shield of 'changing only the external appearance of the creature'.

Just want to say I love this idea, and would extend it to Ranger companions. This could allow a person who really likes Direwolves for example to keep the Direwolf form and just scale it up as they level.

I've long had a similar idea of a Psionic class/subclass that uses customizable Eidolons like in Shadowrun: http://xbox360media.ign.com/xbox360/image/article/782/782217/shadowrun-20070419105323486.jpg

[Fawsto]

Yeah, like 3.5 kind of did for animal companions. The thing is, I rather have a solid set of guidelines to which I can fall back in order to create rules than coming up with rules out of thin air. I like 5.0, really (still fresh, no cluster of splatbooks completely unconcerned with balance, etc), but sometimes I think they kept things a little too clean. Being able to chop classes and monsters in individual parts was kind of nice.

But thx, guys. I will do some reverse engineering on a few monsters (but I already saw that it quite does not work with beasts that much). Btw, DMG says that special senses add nothing to a monster CR. If that is true for 3.5, my bet is that both systems are wrong. Saying that darkvision is meaningless to CR is very close to saying that being blind is meaningless to CR too.

[Rysto]

That's because it's situational. If an encounter is happening in broad daylight, Darkvision has no affect on the CR of the encounter. You need to adjust the CR of an encounter for environmental effects like darkness and how they affect both the PCs and the monsters. Unfortunately there's not a lot of concrete advice for that in the DMG. The best way to account for it is to figure out what the mechanical affects of the environment are and use that for you analysis. For instance, one impact of darkness on a monster without darkvision is that they have disadvantage on their attacks, so when calculating the offensive CR adjust their to-hit value down to account for disadvantage.