Burning

This debuff is activated when touching a fire block (i.e. Hellstone or Meteorite). The player keeps taking damage and their movement speed is reduced until they step off the fire block. Damage is taken at a rate of approximately 30 points per second.

Equipping the Obsidian Skull, the Obsidian Shield, the Obsidian Horseshoe or the Ankh Shield makes the player immune to this debuff.