Burning

Burning is a debuff inflicted when the player comes in contact with Hellstone, Hellstone Brick, or Meteorite. The player takes continuous damage and has their movement speed reduced until they step off the block. Damage is taken at a rate of approximately 30 points per second.

The debuff can be prevented by equipping the Obsidian Skull, Obsidian Shield, Obsidian Horseshoe, Obsidian Water Walking Boots, Lava Waders, or the Ankh Shield, allowing the player to step on the three blocks without taking any damage.

Trivia

 * Prior to 1.3.0.1, all biomes that contain blocks that inflict this debuff had the same music as a Blood Moon.