I started this simulation by creating a point with velocity from the center of the dragon's mouth, and emitting particles from that point. Those particles were then used as a fuel source, with noise added to create some randomness. From there I tweaked the sim, and included both the dragon and the wood block as collision volumes.
The embers were created by bringing in the cached pyro sim to advect particles through it. Color was assigned as a ramp based on the particles life, so they would change from yellow to red as they floated up from the flames. Because Redshift treats particles differently, I had to set up an instance that used the POP points and brought in their attributes, and was then able to copy small spheres to the particles for rendering.
A dynamic burn map was generated using an hda I created. The hda scatters points over the collision geo and the pyro input and calculates where those points meet and allows me to use the previous frame to create a "trail" and make the attribute stay from even after the fire is no longer touching that spot. I brought this attribute into the RS shader and used it to map the burn look into the texture.
All lighting and shading was done in Redshift for Houdini. The volume shader for the pyro was interesting, as Redshift does not have the same settings as Houdini's built-in pyro shader, which assigns colors based on temperature or heat. I had to manually tweak the ramp and colors to get a realistic look. I took this opportunity to learn more about Redshift shaders and built the shader for the dragon as well. The raw renders were tweaked in Nuke using AOVs from Redshift to get the final look.
Dragon model courtesy of the Stanford University Computer Graphics Laboratory.
Wood block model and maps courtesy of CG Trader