Takedown

Takedown is a melee attack in Deus Ex: Human Revolution used to quickly and with guaranteed success dispose of human adversaries. Unlike the previous installments in Deus Ex series this is the only melee "weapon" available to the player. All that is required to initiate a takedown is pressing a special takedown button with least one fully charged energy cell, while being close enough to a target (at 2 meters distance or less). Ensuring cutscene will display Jensen taking down his target with CQC moves or, in case of some lethal takedowns, using his arm-blades. It works flawlessly on every human in the game, bar the bosses (with a single exception).

Overview
Instant Take-Down augmentation is available by default to augmented Adam Jensen and allows him to engage single enemy in one takedown. It can be used from the beginning of the mission in Sarif Manufacturing Plant. During the Introduction yet normal Jensen does not have this ability, so his only combat option is using automatic weapons. Likewise, in The Missing Link the Instant Take-Down is part of Adam's "factory zero" build and can be used from the get-go.

With the Quicksilver Reflex Booster augmentation, Jensen can also take down two targets at once if they are close enough, which yields the normal XP bonuses for the two takedowns with an additional "Two Against One" bonus. A takedown requires one energy cell, whether the player performs it on one or two NPCs.

A takedown can be lethal or non-lethal, the differences being that:
 * 1) Lethal takes more time to initiate: you have to get near the enemy first, then hold the takedown button for 1 second to start it. Meanwhile, with non-lethal takedown you can "mash" the button to attack quickly, which can make a crucial difference when confronting heavily armed hostiles in close quarters.
 * 2) Lethal is noticeably louder: its noise radius is ~25 meters, with non-lethal being almost silent (~1 meter). Hence, it's more likely to put the nearby enemies in a "long alert" state; also, if there are an alarm panels present on the level enemies will try to trigger an alarm upon hearing a death scream.
 * 3) Lethal gives less experience: 30 XP for a single lethal takedown (compared to 50 XP for non-lethal) and 85 XP for a double (compared to 125 XP).
 * 4) Lethal will prevent Pacifist achievement from being awarded.

The only con to using non-lethal is that knocked out enemies can be woken up if they're discovered by their allies. But choosing the target carefully and hiding the bodies will practically eliminate this disadvantage. So, all things considered, there is hardly any reason to choose lethal over non-lethal, except for, maybe, player's desire to role-play or see the special lethal animations.

Every human enemy is dispatched with the same ease, even the most heavily armored and biggest ones, including Ogres, who can withstand up to 100 shots from a combat rifle, but go down after one punch like everyone else. The game plays exactly the same animation for every enemy type, which sometimes leads to comic scenes, like knocking out soldiers equipped with heavy helmets by face slapping or even neck choking.

Attempting to perform a takedown on a boss will cause the boss to counterattack, which will that take off a significant chunk of Adam's health, and should be avoided. Lawrence Barrett will not display a takedown prompt; he will grab and punch Jensen if he gets close enough. Yelena Fedorova will counterattack Jensen's strike with a split kick, even when stunned. Jaron Namir will perform a backflip when engaged normally, but can be defeated in a single takedown if he gets caught while doing a jump over a wall (see the tactics section on character's page).

Considering that the only resource for takedowns is bio-electric energy, which can be recharged indefinitely (one cell at least), the takedowns can be used as a sole weapon throughout the whole game — not to mention such qualities as being quiet, instant and failure-proof. Even as an addition to other weapons they complement every playstyle, especially stealth-oriented or pacifist characters.

Performing a takedown for the first time time will earn player the First Takedown achievement. Performing 50 lethal or non-lethal takedowns on hostile characters (not on civilians) will award the player with the Opportunist achievement. Knocking out 100 enemies with non-lethal takedowns yields the Consciousness is Over-rated achievement. Considering that there are at least 360 enemies in the game it is possible to earn all three achievements being one third into the game, and it's especially easy during a Pacifist playthrough.

Experience
Single takedown: For double takedowns a special experience bonus Two Against One (45 XP) is awarded. Effectively, however, the difference between one double takedown and two single takedowns is 25 XP, since Expedient (20) bonus is awarded only once.
 * Lethal (30): Man Down (10), Expedient (20)
 * Non-lethal (50): Man Down (10), Merciful Soul (20), Expedient (20)

Double takedown:
 * Lethal (85): 2x Man Down (10), Expedient (20), Two Against One (45 XP)
 * Non-lethal (125): 2x Man Down (10), 2x Merciful Soul (20), Expedient (20), Two Against One (45 XP)

Dispatching enemies with non-lethal double takedowns is the most efficient way to earn combat XP, giving 125 XP / 2 = 62.5 XP per enemy. Single takedowns is slightly less effective (50 XP).