Arch Demon

Arch Demons are found in The Underworld in the console version only. In addition to causing physical damage if contacted, they shoot accelerating purple blades at the player, similar to the Demon Scythe spell, in volleys of four. These blades are stopped by barriers such as walls and ash blocks, and have a chance of blinding the player. The blades cannot be destroyed if they are hit by a weapon, unlike the fireballs of the Fire Imp which can be destroyed.

Arch Demons are immune to the On Fire! debuff.

Trivia

 * The Arch Demon's Demon Scythe attack is the only Magic attack produced by an NPC that does not pass through walls; however, the projectile can, in fact, hit players through one-block thick walls.