Wall of Steel

The Wall of Steel is a hardmode boss. It is the Superhardmode trigger boss in Exxo Avalon. To summon it, you must craft a Hellbound Remote, and it can only be fought in Hell.

Boss attacks
It acts similarly to the Wall of Flesh. Upon spawning, it will also have a multitude of Mechanical Hungries. When the Wall of Steel is above 1/3 HP, it will shoot bouncing cursed fireballs and a spread of cursed flame balls from the top eye, and fire lasers from the bottom eye.

Dropping the boss to 1/3 HP will change its AI; it will charge a large, high-damage laser and fire it from the center aperture. It will also shoot cursed flamethrowers from the top eye.

Drops
Upon death, the Wall of Steel drops:


 * 1 Dark Star Heart (per player in the world)
 * 20-25 Souls of Blight

Aftermath
Upon death, Superhardmode begins. The main changes are:


 * Oblivion Ore, Primordial Ore, Opal, and Kunzite are generated.
 * Hallowed Altars can be destroyed with The Banhammer or stronger.
 * Comets can now spawn upon Hallowed Altar destruction, which have Hydrolyth Ore.
 * Various new enemies spawn.
 * The Tropics are generated.

Trivia

 * The Wall of Steel used to be a very widely talked-about idea for mods, although there was never an actual addition of this boss until now.
 * This boss was originally purposed as the Superhardmode trigger for the now paused Exxo Avalon: Origins for Terraria 1.3.
 * Its original sprite was this.
 * Unlike the Wall of Flesh, its top and bottom "eyes" do not look at the player.