Quicksilver Reflex Booster (DXHR)

Quicksilver Reflex Booster is a neuro-mechanical augmentation in Deus Ex: Human Revolution.

In-Game
The Quicksilver Reflex Booster gives player additional option to engage two humans at once in a single take-down, lethal or non-lethal — instead of only one, which is available by default.

To initiate a double take-down you need to be near two humans standing close enough together — normally in a 2 meters radius. If you have "Show Cover/Take-down Prompts" option enabled, it will tell when you can do so by showing a special double take-down symbol on the bottom of the screen.

Note that the system will always target the two closest humans, which can be a nuisance if civilians get targeted by mistake, leaving one of the intended hostile targets unharmed.

Energy cost is the same as for single take-down — 1 energy bar. Noises produced by double take-downs also remain at the same levels: approximately 1 meter for non-lethal and 25 meters for lethal.

Experience
Special experience bonus Two Against One (45 XP) is awarded for taking down two enemies at once. Effectively, however, the bonus from double take-down as compared to two single take-downs is 25 XP, since Expedient (20) bonus is awarded only once.

Single take-down:
 * Lethal (30): Man Down (10), Expedient (20)
 * Non-lethal (50): Man Down (10), Merciful Soul (20), Expedient (20)

Double take-down:
 * 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 take-downs is the most efficient way to earn combat XP, giving 125 XP / 2 = 62.5 XP per enemy.