- In the hands of the Cleric, it is dropped directly onto the ground beneath the player and will quickly explode into a poisonous green gas cloud, choking any monster or player that walks through it. The Cleric's fléchette attack, with its lingering cloud, is considered by most players to be the most effective of the three, especially because he can lure monsters into the gas cloud where they take damage and are easy targets for cheap shots.
- The Mage's fléchettes act in almost exactly the same way as Heretic's Timebomb of the Ancients. They are dropped on the spot where the player stands, and explode for heavy damage after one second.
- When used by the Fighter, it is thrown like a grenade, and will bounce on the ground and explode after three seconds or on contact with a monster. When thrown into water or swamp muck, it will helplessly sink into the liquid with no bouncing or exploding effect.
The fléchette is one of the most common artifacts in the game, and a player may carry 25 at one time. Its hotkey is 5.
When a fléchette is used, the game checks for the player's class, whether it's a Cleric, or if not a Cleric then whether it's a Mage, and if the class is neither Cleric nor Mage then it defaults to Fighter. If a player has been morphed by the Porkalator, because his class is no longer Cleric or Mage, but pig, a morphed Cleric or Mage will throw fléchette grenades like the Fighter does.
- The Cleric's poison clouds have a powerful effect on Centaurs and Slaughtaurs. When they enter the poison, they will start shrieking and be unable to move until the cloud wears off or until they die. Note that while they scream a lot, they are not necessarily taking a lot of damage because their shield is still protecting them. This tactic can additionally be used against the Heresiarch when his reflective shield is up, because the gas cloud still hurts him.
- The Cleric can also combine the fléchette with a Disc of Repulsion to make a projectile attack. Once the gas cloud appears, it can be launched at an enemy with the Disc. If an enemy is hit using this method, it will likely be killed on contact.
- The Fighter can kill Chaos Serpents with two direct hits from fléchettes. Given the rapid rate at which they can be thrown, this is one of the fastest ways a Fighter can kill this enemy short of using Quietus or other artifacts, and is especially helpful early in the game.
- The Mage can use his wand (or other weapon) to injure a Centaur or Slaughtaur so that he goes into his defensive stance, then leave a "surprise" in front of him. With proper spacing and timing, the fléchette will explode just as the Centaur walks onto it, possibly killing it with as little as one wand shot plus a fléchette.
- Gas clouds can still be generated by the Fighter or the Mage, but only by shooting toadstools that may be found in certain areas, such as the Orchard of Lamentations in Episode 3.
- Fléchette means "dart" in French. In English, it refers to a kind of shrapnel first used in WWI.