Eternia Crystal (NPC)

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Desktop/Console/Mobile-Only Content: This information applies only to the Desktop, Console, and Mobile versions of Terraria.
This article is about the NPC. For the item used to start the event, see Eternia Crystal.

Of course, you can't let the Old One's Army destroy the Eternia Crystal! This will have catastrophic consequences for my home world of Etheria!

Emote Town Bartender.gif The Tavernkeep

The Eternia Crystal in its stand.

The Eternia Crystal is a background object that acts as the centerpiece of the Old One's Army event.

Pressing Use / Attack on the Eternia Crystal Stand with an Eternia Crystal in the player's inventory will place the Eternia Crystal on the stand. A long, flat area is required in order to place the Eternia Crystal successfully and summon the event; otherwise, the Eternia Crystal will not be placed. Once this is done, two Mysterious Portals will appear far away from either side of the Eternia Crystal, and, after a 5-second countdown, the Eternia Crystal (now considered an NPC) must be protected from waves of enemies from the Old One's Army who will prioritize attacking it. If the Crystal is destroyed, the event ends in failure. If it is kept "alive" until all waves are cleared, the event is won.

The Eternia Crystal can be purchased from the Tavernkeep for 25 SC (pre-any mechanical boss) / 1 GC (post-any mechanical boss) / 4 GC (post-Golem).


  • A minimum of 61 tiles of flat space is required on either side of the Eternia Crystal Stand, measured from the column clicked.
    • If adequate space has not been provided to either side of the Eternia Crystal Stand, the game will announce the following status message: "The eternia crystal rejects this area and pops away instantly, the Tavernkeep mentioned it should rest in a large flat open area..."
  • Once the Eternia Crystal is placed, nearby players are inflicted with the Creative Shock debuff for the duration of the Old One's Army event, which prevents the removal or placement of blocks during the entire event. The area in which the debuff is active generally depends on the positions of the Mysterious Portals (see Creative Shock § Notes for details). The Ice Rod can still be used, but it will not block enemies since they can phase through blocks.
  • The Eternia Crystal's health and defense are dependent on the world's tier: pre-any mechanical boss, post-any mechanical boss, and post-Golem. It should be noted that although its health and defense increase with each tier, so does enemy attack damage, as the enemies become increasingly more difficult and more numerous with each tier.
  • Though the Eternia Crystal itself is immune to explosive damage, the Eternia Crystal Stand and the blocks beneath it can be broken by the explosion. This will cause the Eternia Crystal NPC to fall until it lands on a solid block once again.
  • The Eternia Crystal NPC can be moved by hoiks. If utilized correctly, this can make the fight much easier.
  • The Eternia Crystal NPC can be damaged by Rotten Eggs, so care should be taken if they are utilized as a weapon during the event.


  • The Eternia Crystal's map icon is the same as its inventory sprite.
  • The Eternia Crystal's sprite will have cracks appear in it as its health decreases.
  • The Eternia Crystal has two related projectiles called "Grim End" (ID 672) and "Victory!" (ID 713). Their only purpose is to create visual effects when the event is either lost or won.


  • Desktop
    • T3 health reduced from 10000 to 5000.
    • T3 defense reduced from 45 to 20.