Charcoal is a Composition Type that is healed instead of damaged by the Horrible Burning spell. Charcoal creatures can cast Horrible Burning on the player without deducting their mana. They are, however, extremely vulnerable to other types of magic, with a +10% success rate and 140-170% the rate of normal damage, making them easy fodder for players looking to avoid direct confrontation. Base physical damage is not modified, but there is a 1 in 4 chance that a player adjacent to a charcoal creature will pass out from the heat, rendering them vulnerable to attack (again, making close-quarters combat not a good idea).
Flesh creatures besides the player who get too close to a charcoal creature have a 1 in 3 chance of being cooked, converting their corpse into safe eats.