Blackfire clay

This pliant black clay is always pleasantly warm to the touch. Working blackfire clay in your hands for a full round causes the clay to grow much warmer, granting you a +4 alchemical bonus on saving throws made to resist cold weather. You can combine five blocks of clay over the course of a minute to produce a source of warmth equivalent to a small campfire, allowing you to heat a campsite and cook food.

Blackfire clay only produces heat, never light, smoke, or odor. The clay emits warmth for 1 hour before hardening into an unusable lump. A newly created brick of blackfire clay is composed of 10 blocks.