The Twins in Terraria is a pair of floating eyes, similar to the Eye of Cthulhu pre-Hardmode boss. But this Hardmode version brings additional tricks to the table at players' expense. Worse, The Twins must also be defeated before a time limit runs out, or else it despawns and players must try again. To help get it right the first time, here's how to summon The Twins in Terraria, all of their attacks, and the loot you can gain by defeating them.

How to Summon The Twins in Terraria

Summoning this Hardmode exclusive boss requires players to destroy a Crimson or Demon Altar. However, the boss still only has a 10% chance of appearing. You’ll know if this action is successful if you see the words, “This is going to be a terrible night…” appearing at the bottom left corner of the screen. Alternatively, players can craft the Mechanical Eye item near a Mythril or Orichalcum Anvil using the following materials:

• 3x Lens
• 5x Iron Bar (any type)
• 6x Soul of Light

Attempting to summon The Twins during the day won’t yield results, even when using the Mechanical Eye, though the item will remain in the player’s inventory. Note: It’s possible to summon The Twins in a pre-Hardmode world. A player would only need to bring the Mechanical Eye item to that world and use it at night. It’s also not advisable to challenge this boss as a beginner.

How to Beat The Twins (Attacks, Phases)

The Twins are two “eyes,” named Retinazer and Spazmatism, who will start the battle off with ranged attacks. They’ll shift to trying to ram players when each eye enters its second phase. That also means that Retinazer and Spazmatism have separate health bars that players must handle accordingly. With this in mind, try your best to focus on one eye first before moving to the other as a way to limit incoming damage. Note: The Twins make a cameo appearance in the Don’t Starve Together x Terraria crossover event, “An Eye For An Eye.”

All Attacks

Like the pre-Hardmode counterpart, Eye of Cthulhu, The Twins only have a few attacks and only change their behaviors when their health reaches below 40%. The attacks for the first phase are:

• Retinazer fires lasers
• Spazmatism fires Cursed Flame balls

Once either eye’s health drops below 40%, it’ll change its form and attack pattern. For Retinazer, a laser cannon appears from its mouth/pupil. As for Spazmatism, its eye “opens,” revealing a mouth. The attacks for the second phase are:

• Retinazer fires more powerful lasers and will increase in intensity as its health drops
• Spazmatism charges at the player’s position with great speed and range, and will sometimes spew out Cursed Flame balls

If a player fights this boss in Expert Mode, The Twins’ attacks become more furious and deal more damage. There are also slight changes to their behaviors:

• Retinazer’s lasers fire faster
• Spazmatism’s Cursed Flame inflicts the Cursed Inferno debuff, preventing natural health regeneration while causing damage over time.

Defeating The Twins brings the player one step closer to fighting the game’s final boss, Moon Lord. But you must defeat the Plantera and Golem bosses first.

Loot Table

• Soul of Sight
• Hallowed Bar
• Twin Mask
• Greater Healing Potion