When you roll a 20 on an attack roll made with this magic weapon the creatures takes +4 purple fire damage then the arrow explodes, all enemies in 5 feets from the location of the explosion also take the extra damage (enemy creatures only).

The Purple Emperor also has 3 charge. While attuned to it, you can expend the charge and make a ranged weapon attack with the Purple Emperor, when you load the bow with an arrow the arrow turns into a purple fire projectile. If the attack hits, the creature takes the normal damage of the weapon +4 purple fire damage then the arrow explodes, all enemies in 5 feets from the location of the explosion also take the extra damage (enemy creatures only).

If the attack misses the target, you loss the charge and the creature takes no damage.

The Purple Emperor regains 1d3 expended charge when you complete a Long Rest.

Proficiency with a Longbow allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Damage: Fire, Damage, Buff, Combat, Ammunition, Heavy, Range, Two-Handed, Slow