Weapons with the burning fusion often take on an appearance that includes numerous flame-like elements.
However, if applied to a weapon that already has visual details representing crows or ravens, the fusion adds further raven-like flourishes to the weapon instead. A weapon with the burning fusion gains the burn critical hit effect. The burn damage for the critical hit effect is 1d6 when the fusion is applied to a 4th- or 5th-level weapon, 2d6 when applied to 6th- to 10th-level weapons, 3d6 when applied to 11th- to 15th-level weapons, and 4d6 when applied 16th- to 20th-level weapons. If the weapon already has a critical hit effect, you can apply either the weapon’s normal critical hit effect or the burn critical hit effect when you score a critical hit.