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Determining base Creature Identification DC

The combination of certain feats and skill tricks along with various wordings of the description of the Knowledge skill require further clarification as to what a monster's base identification DC should be based upon type and frequency as well as its challenge rating and air of mystery. This number is especially important in regards to the Knowledge Devotion™ feat as found in the Complete Champion (© Wizards of the Coast, 2007).

Note that this is a work in progress and information within this page may change at any time.

Base Difficulty Level

The base DC of identifying a monster is it's type or sub type. Note that these numbers are initial evaluations, play testing may result in different numbers in the near future. However, no monster type DC will ever drop below 10.

Monster Type Base DC Monster Type Base DC
Aberration 15 Magical Beast 15
Animal 10 Ooze 12
Construct 15 Outsider 18
Dragon 18 Plant 12
Elemental 18 Undead-Corporeal 12
Fey 15 Undead-Incorporeal 15
Giant 12 Vermin 10
Humanoid 10  

Frequency

Frequency Modifier
Common +0
Uncommon +2
Rare +5
Very Rare +10

A feature of monster statistics in the past (1st and 2nd edition Advanced Dungeons & Dragons), this modifier requires some judgement on the part of the DM. Previous versions will be reviewed as well as consideration to the current campaign world of Amastasia. Factors such as the monster's normal environment also come into play as well. A Frost Giant may be uncommon in the snow covered Northern Growlers but very rare in the southern Amastasian Mountains. The rationale for this modifier is that a character may expect to find certain creatures in certain environments, and as a result find it harder to identify them in other locales. Thus, a creature that is common in a locale or environment may automatically be considered at least one rank higher (rarity or less frequent) in other environments.

For example, a Dretch demon may be considered Common in the Abyss, but rare on the Prime Material Plane. So it's Base DC is 18 for being an outsider and a modifer of +5 is added for frequency when encountered on the Amastasian continent for a base DC of 23 to identify it as such.

Challenge Rating

The Knowledge skill description states that the base DC to identify a monster is 10 + the monster's Hit Dice. However, monsters whose hit dice vary by class or size can change drastically while the Challenge Rating varies little. As a result, the DC to identify a monster will be it's base DC based on type, modifiers for frequency, and modified by adding it's CR with the following caveats. Monsters with less than 1/2 CR are treated as having a CR of 0 for this check. Monsters with 1/2 to 1 CR are treated as having a CR of 1.

Another issue with dealing with either Hit Dice or CR is that of class levels. Obviously Barbarians have different strengths and weaknesses compared to Wizards, so does a knowledge skill or Feat based on that skill need to take that into effect? Humans generally have the same strengths and weaknesses physically, but knowing that wizards are generally unarmored and will rely on spell casting to defend themselves may be useful. Class levels generally increase Challenge Ratings on a nearly one to one basis, so how does that come into play?