Call of Cthulhu to AD&D 1e Conversion

Call of Cthulhu Creatures to AD&D First Edition The following simple guidelines can be used to easily convert monsters from your Basic Role Playing Call of Cthulhu books for use in your AD&D First Edition campaigns. As with all mechanical conversions from one role playing system to another, some small sacrifices were necessary here, but they should not be immediately obvious, nor should they hinder actual play. There are quite a few creature attributes in Call of Cthulhu that simply have no counterpart in AD&D (e.g., STR, POW, POW, APP, etc) thus those things can be safely ignored and do not need to be converted. Those attributes of  a creature that can be converted and that do have a counterpart in AD&D have been addressed below.

 Armor Class: Subtract CoC creature's Armor Points from 10. Move: Add two to CoC creature's Move. Hit Dice: Subtract 12 from CoC creature's average CON (minimum of one). Damage/Attack: As specified in CoC. Special Attack/Defenses (Including Spells): As specified in CoC, but choose spells from AD&D lists. Magical Resistance: As specified in CoC. Intelligence: Subtract one from CoC creature's average INT rating. Size: A SIZ of 1 indicates a Tiny AD&D creature, a SIZ of 2-4 indicates a Small AD&D creature, a SIZ of 5-17 indicates a roughly man-sized AD&D creature, and a SIZ of 18 or higher indicates a Large AD&D creature. Experience point values for a creature are calculated using that creature's AD&D hit dice value adjusted for special attacks and defenses, as discussed in the AD&D DMG. DMG.

 Artwork by Maciej Zagorski, used by permission of The Forge Studios.