On Fire!

On Fire! is a debuff which causes the afflicted NPC or player to lose 4 health per second while not regenerating health. This debuff can be canceled prematurely by jumping into Water, or by pouring a Water Bucket over the player's head. If the player is under the effects of the Obsidian Skin Potion, Lava will not burn them.

Immune NPCs

 * Meteor Head
 * Fire Imp
 * Angry Bones (and variations)
 * Dark Caster
 * Cursed Skull
 * Skeletron
 * Bone Serpent
 * Undead Miner
 * Tim
 * Lava Slime
 * Hellbat
 * Demon
 * Voodoo Demon
 * Dungeon Guardian
 * Pixie
 * Wraith
 * Cursed Hammer
 * Enchanted Sword
 * Mimic
 * Wyvern
 * Wall of Flesh
 * Chaos Elemental
 * Skeletron Prime
 * The Destroyer
 * Illuminant Bat
 * Illuminant Slime
 * Possessed Armor