Backstab
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— The Spy
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A backstab is a context-sensitive attack that a Spy can perform with any of his melee weapons. When a Spy uses any one of his knives to hit an enemy from behind, a successful backstab is performed, resulting in an instant kill in almost all cases. Backstabs deal no damage to enemies with invulnerability effects, such as those under the effects of a standard ÜberCharge, though the Spy still raises his knife and performs the usual backstab animation.
Contents
Mechanism
To indicate that a Spy is within the required range and angle to perform a backstab, he raises his knife and turns it downward, primed for a kill. The knife remains in this position until the target is no longer in reach, which is 40 Hammer units to the target's back, or the Spy attempts a backstab by attacking. The knife turns downward even if positioned behind a cloaked or disguised enemy Spy. As the Spy's melee weapons do not have a delay between the swing being initiated and the damage being dealt, as long as the knife is pointed downward, the Spy simply needs to attack for an instant kill to occur.
Should a Spy perform a melee attack that connects with an enemy while he is behind said enemy, a backstab occurs. Backstabs deal damage equal to 200% of the target's current health and are always Critical hits, resulting in a total damage of six times the victim's current health; while the critical damage can be negated, this does not stop the stab from being lethal unless the target has significant additional protection.
A backstab triggers as long as the Spy is behind an enemy (ignoring verticality, meaning he can backstab if above or below an enemy) and the enemy is facing roughly away from him. The Spy can backstab in an approximately 180 degree radius around the enemy's back, which means a Spy facing an enemy's side is still capable of backstabbing that enemy. The game considers the Spy to be facing the same direction as the enemy as long as the crosshairs of both these players are pointing in directions within 107.4 degrees from each other.
More precisely, the game checks for several dot products (a formula to check if two things are facing the same direction. The outcome is a number between 1 and -1, with 1 meaning they face the same direction and -1 meaning they face each other) before allowing a backstab. The game checks if:
- The dot product between a vector from the Spy's position to the enemy's position and the direction the enemy is facing is larger than 0 — this means that the Spy needs to be behind the enemy.
- The dot product between the vector from the Spy's position to the enemy's position and the direction the Spy is facing is larger than 0.5 — this means that the Spy's crosshair cannot be aimed more than ~54-64 degrees away from the victim's back.
- The dot product between the direction the enemy's crosshair is facing and the direction the Spy's crosshair is facing is larger than -0.3 — this means that the Spy and enemy cannot be facing each other.[1]
If all of these conditions are met, the game allows for a backstab.
Like normal melee attacks, backstabs can be performed while disguised, though the Spy proceeds to lose his disguise whether the attack connects or not. Backstabs are nothing more than pure damage, and so cannot injure or kill invulnerable players. Buildings and Halloween bosses cannot be backstabbed.
Robots in Mann vs. Machine can be backstabbed just as normal players. In addition to this, if a robot is sapped, it can be backstabbed from any direction, not just from behind. However, giant robots operate much differently. Backstabbing a giant has a base damage of 750, but this is reduced to 25% of that (188) by default; each armor penetration upgrade restores 25% of the base damage, up to 125% of the base (938). Spies must therefore upgrade their knife in order to have a chance at taking out giant robots.
In Versus Saxton Hale, backstabs deal a fraction of the overall damage to Saxton Hale and causes the Spy to flinch for 2.0s.
Various weapons affect backstabs in some fashion:
- Backstabbing with Your Eternal Reward or the Wanga Prick causes a silent death. The victim does not scream, their body vanishes, and no killfeed notification is given to the victim's teammates. The attacking Spy disguises as the fallen enemy almost instantly.
- Backstabbing with the Conniver's Kunai takes the victim's remaining health (or 75 health if the victim has less than 75 health) and gives it to the Spy, up to a maximum of 210. This is offset by a lowered base health.
- Backstabbing with the Big Earner fills the Spy's Cloak meter by 30%, regardless of which cloaking device is equipped. A backstab with this weapon also gives the Spy a three-second speed boost.
- Backstabbing with the Spy-Cicle turns enemy ragdolls into an ice statue, which also creates a loud freezing/cracking noise, in addition to the usual victim screams.
- Attempting to backstab a Sniper wearing the Razorback results in the backstab being blocked, in addition to preventing the Spy from attacking, cloaking, or switching weapons for 2 seconds afterward. Thus, the Razorback makes Snipers less prone to backstabs and encourages Spies to use their selected revolver instead.
Backstabbing techniques
There are various backstabbing techniques, also known as "trickstabs", that Spies can perform. Some techniques are rather basic, while some require more advance movement or precise timing. Below is a list of trickstabs commonly used by Spies:
- Stab-and-Sap or Sap-and-Stab: This technique involves backstabbing an Engineer, then switching to the Sapper and sapping the buildings or vice versa. When stabbing first, it must be done quickly enough to prevent the Sentry Gun from turning around and shooting the Spy. More experienced Spies may wait for the Sentry Gun to be fully turned away before stabbing. The Your Eternal Reward's instant disguise on backstab makes this technique much easier. Spies approaching without a disguise must take care, as a Sentry Gun does not stop shooting at them once they are disguised but only once line of sight is broken. A wrangled Sentry Gun is disabled for three seconds after the Engineer's death, making it much easier to perform a Stab-and-Sap.
- Topstab, Dropstab, or Stairstab: This backstabbing technique involves dropping onto or standing on top of an enemy player's head and backstabbing them. A dropstab typically involves dropping down from a high-up place onto or just behind an enemy. It can also be performed by surfing damage from an enemy, such as a rocket, then landing on top or right behind them (known as a "surfstab"). A topstab simply involves being on top of the player's head, such as a turtling Engineer or a Sniper aiming down the scope with his back against a wall. A stairstab is performed by jumping over the enemy's head from any kind of elevation (usually stairs), including Teleporters or uneven ground.
- Quickstab: While an unaware enemy is running towards you, let them run past you before spinning and stabbing their retreating back. This is one of the only reliable methods of backstabbing Scouts or any enemy that believes your disguise.
- Matador stab or Cornerstab: This technique involves tricking an enemy into turning in your direction by pretending to run around them one way, then quickly moving back and strafing (using left/right movement keys) into backstabbing range as they turn toward you. A matador stab can be performed anywhere, while a cornerstab is performed around corners where the enemy is taking a tight turn and you take a wide turn.
- Sidestab: A side stab is accomplished by taking advantage of the wide backstab angle and effectively backstabbing an enemy from the side. This technique can also be done on slow, backpedaling enemies by walking alongside them while facing the same direction. For enemies who are attempting to strafe behind the Spy, the Spy matches the enemy's movement by holding S and a strafe key, and attempts a sidestab while backpedaling.
- Circlestrafe stab: A difficult type of trickstab that is designed to counter strafing enemies who do not turn enough to fall for a matador stab. Circlestrafing relies on strafing in a circle around a moving enemy and eventually backstabbing them as they attempt to track your movement. This technique is often used on enemies engaging in a melee fight or otherwise fighting in close quarters while pursuing the Spy.
- Airstab: A backstab which is performed while both the Spy and the enemy are airborne. The Spy quickly flicks his aim to the enemy's back and then stabs. To prevent the loss of momentum while airborne due to bumping, strafe around the enemy and then stab. This stab can also be performed while attempting a dropstab, such as when an enemy explosive jumps upwards while the Spy drops down and stabs them mid-air.
Issues
- Due to a glitch in the game, a stab that has appeared to have occurred from the front can sometimes be rendered as a backstab. Known more commonly as a facestab, these kills are now mostly the result of lag compensation by the game engine itself. Prior to many game patches, facestabs were more common due to bugs in how the game detects a backstab. Facestabs take two forms: the "valid" stab and the "true" facestab. Most of what the recipient sees as a facestab is usually either a cornerstab or a sidestab, where on the Spy's screen, he sees it as attacking the target's back, but due to lag, the target sees the Spy attacking from the front. A valid facestab works as intended by the developers, making correct use of lag compensation. In a true facestab, the Spy appears to be attacking an enemy from the front on both players' screens, but lag compensation results in it being registered as a backstab. This is considered a bug.
- Another community-coined term is the failstab, which refers to a backstab which should have succeeded, but instead did only normal Knife damage, despite the backstab animation playing fully and the Knife connecting. These stabs are almost always linked to the latency conditions between the server and the player. A similar variant is a stab that plays the animation and the sound effect, but does no actual damage.
- Rarely, during taunts, the player's 'back' changes position; it becomes directly behind the player's 3rd-person camera, which means that players can avoid backstabs by moving the camera away from the Spy. This generally occurs by accident; for example, when a player positions the camera in front of them to watch the taunt themselves, making their back into their front. Facestabs can also rarely occur this way.
- The angle required for a backstab is based on the direction the victim is looking; however, all players have models whose normal stance has their backs rotated to the left slightly, due to the way they carry their respective weapons (this is most prominent with Heavies). This means that at certain angles the player appears to be stabbing their target in the back, when in fact the player is not inside the 180 degree angle for backstabs. Equally, there are valid backstab positions which appear to have the player stabbing slightly into the front of their victim. These hit-box positions can be determined by the shoulders of the character models.
Related achievements
Soldier
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Sniper
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Spy
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Update history
- Fixed a Spy backstab exploit where you could stab a player who was not facing away from you.
- Fixed a case where a Spy stabbing from the front of a player would score a backstab.
- Fixed Spy backstab exploit.
February 24, 2009 Patch (Scout Update)
- Changed backstab handling to fix facestabs.
- [Undocumented] Reduced stab radius to 160 degrees. Removed quickbackstabs and thus reduced the Spy's backstab range (Has since been reverted). Made backstabs quicker.
- Increased backstab check so that Spies can side-stab again.
May 21, 2009 Patch (Sniper vs. Spy Update)
- The Heavy and Sniper now have new custom death animations.
- Added a backstab custom death animation to the Heavy.
- Fixed a couple of cases where viable backstabs would fail.
August 13, 2009 Patch (Classless Update)
- Cloaked Spies standing in valid backstab positions no longer raise their Knife.
December 17, 2009 Patch (WAR! Update)
- Added more backstab animations.
- Added backstab death animations for Scout, Spy, Medic, Demoman, Engineer, and Pyro. All death animations have a 25% chance to play.
- Fixed a glitch where the Spy would take fall damage after backstabbing someone while standing on top of him.
- Fixed the knife not playing its backstab animation when Crits are disabled.
Bugs
- When a player for the opposing team is standing on top of the Spy, the Spy can always perform a successful backstab regardless as to whether or not the Spy's aim falls within the regular backstab radius.
- Occasionally, when swiping at an enemy, the Spy does the backstab animation, even if it was not a backstab.
- Occasionally, a Spy takes fall damage after backstabbing someone while standing on top of the victim, even though this was supposedly fixed in the October 18, 2011 Patch.
Trivia
- Originally, the Spy's backstab animation was just over a second long and manifested as the current animation, but was slowed down. This was changed to the current, sped up version used today in the interests of balance. Before this change, skilled Spies would "quick-stab". This involved staying out of backstab range of the victim, and then swinging the Knife just before entering backstab range, thereby bypassing the backstab animation, but still rewarding an instant kill.
- The Sniper's unique backstab death animation was first seen in Trailer 2 before any backstab animations were integrated into the game.
External links
References
- ↑ game\shared\tf\tf_weapon_knife.cpp:L395-430
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