TAC-15 a crossbow fitted with zoom scope, using special arrows as ammunition. Unlike most other FPS game, the crossbow does not come with arrow mag, so players can only fire one arrow at a time before they need to nock another one in. The crossbow has wide crosshair (like shotguns) when brought out; players are required to "charge" their shot (holding LMB) for a few seconds to achieve 100% accuracy (The arrow will fly straight to the target regardless of their movement and/or players' movement).
TAC-15 is given to Hunter class as their special skill. It uses special tracking dart arrow mixed with poison (Similar to Medic's Grenade). When an opponent is hit, the arrow will track their location while continuously releasing poison around them which drain their HPs slowly, plus during this time they can't receive treatment from teammates Medic. The effect lasts for about 10 seconds and can be extended by enhancing Hunter class card. Comes equipped with a 1-level zoom scope, allowing it to act as a sniper rifle at distance (since it makes no noise, it's pretty useful for picking off unsuspecting players).
The TAC-15 is provided as special support weapon against Blaze in Round 31 - it's also available in God's Arena. Titled "Mesh gun", this crossbow now fires a flaming arrow that carries a mesh net, which cover the boss, slowing his movement whilst dealing some damage. It has three shots and players can fire them all at once without having to reload.
Another special variant is available in EMD Lab (Hard difficulty). During the battle against Geared Serpent, when players' berserk bar is full, pressing F will give them a TAC-15 crossbow with one colored arrow. This arrow, when hit Serpent's body part in the same color, will instantly break it and deal major damage.