This is an addon mod for both Incendium and Boss Checklist that integrates the former's Hovering Inferno boss into the latter's boss checklist interface as an entry.

"How did you make this work? Incendium is a data pack bundled as a mod!"

To begin with, the mod adds a fake, unspawnable stand-in entity which acts as the foundation for the boss checklist entry you see. The custom drops displayed in the "drops" category in the entry are likewise, fake, unobtainable items designed to replicate the real deal. The boss's entry is automatically marked as defeated once a player is detected to have earned the advancement attributed to defeating the boss.

"Why isn't this bundled with your other Boss Checklist addons?"

This mod uses an aforementioned fake entity that is added by this mod itself. Thus, the Hovering Inferno entry added by this mod will appear regardless of whether or not you actually have the Incendium mod installed. You wouldn't want a modpack where players would go around curiously searching for this "Hovering Inferno" only to figure out later down the line that they do not even have the mod supposedly accommodating the boss installed in the first place.

This addon includes textures and models from Sparkles by Stardust Labs, licensed under the BSD 3-Clause License.

Sparkles resource pack: https://modrinth.com/resourcepack/sparkles

Boss Checklist - Incendium Compatibility