Homebrew, Monstrous Compendium Annual Volume I (2e)
Innate Spellcasting. The blazing bones' innate spellcasting ability is Intelligence (spell save DC 12, +4 spell attack bonus). It can innately cast the following spells, requiring no material components:
Death Throes. When the blazing bones dies, it explodes, and each creature within 10' of it must make a DC 12 Dexterity saving throw, taking 14 (4d6) fire damage on a failed save, or half as much damage on a successful one. The explosion ignites flammable objects in that area that aren't being worn or carried.
Fire Absorption. Whenever the blazing bones is subjected to fire damage, it takes no damage & instead regains a number of hit points equal to the fire damage dealt.
Fire Aura. At the start of each of the blazing bones' turns, each creature within 5' of it takes 5 (1d10) fire damage, & flammable objects in the aura that aren't being worn or carried ignite. A creature that touches the blazing bones or hits it with a melee attack while within 5' of it takes 5 (1d10) fire damage.
Heated Weapons. When the blazing bones hits with a melee weapon, it deals an extra 3 (1d6) fire damage (included in the attack).
Holy Water Vulnerability. If splashed with the contents of a flask of holy water or hit with a bottle of holy water, the blazing bones takes double damage.
Illumination. The blazing bones sheds bright light in a 10' radius & dim light for an additional 10'.
Slam. Melee Weapon Attack +2 to hit, reach 5', one target. Hit: 3 (1d6) bludgeoning & 3 (1d6) fire damage.
Fireblast (Recharge 5-6). The blazing bones creates an explosion of flame in a 10' radius sphere centered on itself. All creatures in that radius must make a DC 12 Dexterity saving throw. A target takes 14 (4d6) fire damage on a failed save, or half as much damage on a successful one.
The fire spreads around corners. It ignites flammable objects in the area that aren't being worn or carried.
Any Climate & Any Terrain