Fire Works is a Pack-a-Punch upgrade in Call of Duty: Black Ops III. It allows the weapon to shoot a bullet that will kill the affected zombie, releasing fireworks from its body, with a model of the weapon used appearing in the air and shooting any zombies within its line of sight.
The zombie on which the effect is triggered is killed instantly, while any zombies targeted by the weapon thereafter are killed within a couple seconds. While it does not cause instant death like Dead Wire or Thunder Wall, it does kill zombies faster than Blast Furnace.
Fire Works is a very powerful perk, able to take out entire groups of zombies if they are all bunched together, similarly to Blast Furnace. Unlike Blast Furnace, however, Fire Works will also target zombies across a room or open space as long as they are in line of sight from the initial affected zombie. There is an upper limit on the distance the effect will reach, however.
Fire Works has a long cooldown for its effect, similar to Blast Furnace (15-20 seconds). It will kill zombies at any round, similarly to the other Pack-a-Punch upgrades. This makes it an excellent choice for clearing rooms and avoiding getting trapped by large groups of zombies at high rounds.
The zombie on which the effect is triggered will give the player points, but any zombies killed afterward will not generate any points. If a player is looking to gain points, another perk such as Blast Furnace or Dead Wire may be preferable.