So, a lot of mods use various blocks as heat sources to work, everything from fire, lava, magma blocks, and campfires, to their own modded blocks. And they all basically use their own tags, or simply check for specific blocks, to determine if the block is hot. My proposal is to add an universal tag for this, allowing for cross mod compatibility without explicitly adding support to the mod. This would also reduce the amount of tags blocks would be given, as every mod would not require to create their own tag. Edit: Active Furnaces should also be given the tag, I believe: