The Sharpened Darts Lab is a SupportMonkeycard in Bloons Card Storm, introduced in version 4.0. It is temporary and instead of being able to attack, each time the player plays a Primary Monkey, it consumes 1 ammo and causes that Monkey to attack a random enemy Bloon, without consuming its ammo. The attack triggers before the Monkey receives any ATK modifiers from other Monkeys (e.g. Dart Monkey Twins or Monkey Village) or being on Game Night. The attack inherits any bonuses that Monkey has (e.g. Spike-o-Pult's scaling per pop, Missile Launcher's double attack, Sharp Shooter's first shot bonus). The Sharpened Darts Lab's ammo still is consumed if no enemy Bloons are on their side.
For its price, it's fairly strong as a secondary source of damage, provided Primary Monkeys with high Attack Power are used.
Bomb Shooter is a cheap but efficient choice. Bomb Bloon's bonus Bomb Shooters synergizes with this dual combo.
Because Sharpened Darts Lab is affected by the card effects of Primary Monkeys, Sharp Shooter and Missile Launcher are good candidates for the high damage. So is Frag Bomb Shooter if there's many Bloons. Also, Spike-o-Pult can scale with a minor headstart if able to pop a weakened Bloon.