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Psycho Knife
  • Psycho Knife item sprite
Stack digit 1.png
Damage85 / 70 (Melee)
Knockback3.5 (Weak)
Critical chance4%
Use time8 (Insanely fast) /
20 (Very fast)
TooltipAllows you to go into stealth mode
RarityRarity level: 8
Research1 required
Obtained from Obtained from
Classic mode icon.png Classic
Expert mode icon.png Expert
Master mode icon.png Master

The Psycho Knife in use. Note the increased damage after stealth mode, and massively increased use speed.

The Psycho Knife in use, pre- Note the increased damage after stealth mode, and slower use speed.

The Psycho Knife is a Hardmode, post-Plantera melee weapon that has a 2.5*1/40 (2.5%) / 4.94*79/1600 (4.94%) chance to be dropped by the Psycho during the Solar Eclipse event. When holding the Psycho Knife and standing still, the player will quickly enter stealth mode, causing them to turn almost completely transparent, move much more slowly, and no longer be targeted by enemies.

Stealth mode is engaged gradually over the course of about one second, during which the weapon's stats are steadily boosted up to the following values:

Stealth mode is disengaged when successfully attacking an enemy, when switching to a different weapon or when riding a mount. Swinging the weapon alone does not cancel stealth, nor does walking or flying. Standing still again afterward re-engages it. Moving or swinging the weapon during the one-second transition period, however, will cancel stealth mode.

Its best modifier is Legendary. Due to rounding, the Light modifier gives the same speed bonus as Legendary, with fewer other bonuses.


  • The Psycho Knife only receives 33% of any melee speed bonus.
  • At a base level, the Psycho Knife is tied with the Fetid Baghnakhs for the title of "fastest melee weapon in the game". However, given the Baghnakhs' 75% melee speed bonus reduction compared to the Psycho Knife's 66% melee speed bonus reduction, the Psycho Knife is capable of reaching higher speeds overall, thus making it functionally the fastest melee weapon in the game.
  • The stealth mode that is activated by the Psycho Knife is somewhat similar to that of the Shroomite armor's set bonus, in that both stealth bonuses activate while remaining still for a period of time.
    • However, more akin to Vortex armor, moving will not deactivate it.
  • The horizontal speed reduction applies even whilst using wings to fly. Vertical flight speed, however, remains unaffected.
  • All melee weapons are affected by the increased stats from stealth mode; however, you never see this effect in-game, as if you attempt to switch weapons, the stealth bonus will no longer apply.
  • The dash attacks that can be used with the Solar Flare armor's set bonus and the Shield of Cthulhu gain the damage bonus from the Psycho Knife's stealth.
  • Other players can see a player that is using Psycho Knife's stealth if they are missing health, as the health bar will be shown above their head.
  • If the user enters stealth, holds the attack button to autoswing their Psycho Knife, and uses the Quick Mount function, they will retain stealth while using their mount until an enemy is hit by the weapon or they stop swinging.
  • Enemies which fire projectiles and certain flying enemies will target through stealth.
    • Projectile firing enemies will not, however, chase the stealthed player.


  • Melee weapon projectile stats from any weapon will be boosted during stealth, which can be useful for dispatching large groups of enemies while maintaining a distance.
    • As an example, using a melee weapon that shoots projectiles, such as the Terra Blade or the Meowmere, and switching to Psycho Knife before the projectile hits will result in extreme damage to enemies hit if stealth builds up before the projectile strikes. The Meowmere uses this to especially great effect due to its projectiles being able to hit many times before dissipating.
  • By gaining the Striking Moment buff from the Brand of the Inferno before switching to the Psycho Knife, one can easily deal over 2,000 damage in a single hit if it is a critical hit.
    • This damage can be drastically increased to well over 7,000 in a single hit when utilizing banners in Expert Mode alongside damage boosting gear such as armor and accessories, marking it one of the highest damaging setups in the game.
  • A hook or any dash accessory (Shield of Cthulhu, Master Ninja Gear or Tabi) can be used to great effect to move faster while in stealth mode. Simply hook the floor while in stealth mode and jump; it will boost your movement speed significantly.


  • If buffed correctly, the Psycho Knife can achieve more damage than the Zenith.


  • Desktop
    • Damage increased from 70 to 85.
    • Use time decreased from 20 to 8.
    • Now only gains 33% benefit from increased melee speed stats.