The Laser Cannon increases its pierce from 1 to 4 (6 with Powerful Darts), pops 2 layers, and converts the main attack to the energy damage type (can pop Frozen Bloons but can no longer pop Purple Bloons without support). In addition, the Laser Shock effect lasts for 2 seconds instead of just 1 second. Random projectile deviation remains at ~4° each side.
It costs $3,615 on Easy, $4,250 on Medium, $4,590 on Hard, and $5,100 on Impoppable.
Laser Cannon is suitable as an early mid-game option due to its decent stats and infinite range. It functions best on maps with straight lines so it can miss less. Try to keep in mind the fact that it is relatively weak early game as a low tier Dartling Gunner. It is used as a good stepping stone to Plasma Accelerator.
3-2-0 Laser Cannon is mostly preferred for maximum DPS as it grants camo detection and faster attack speed. Laser Cannon has decent pierce already, but with Powerful Darts it can reach its targets at further distances much sooner with increased pierce, which can make 3-0-2 Laser Cannon better than 3-2-0 Laser Cannon in some cases.
Because Laser Cannon pops neither Purples nor Leads, make sure to have support towers for those types so that Laser Cannon can struggle less against the two weaknesses.
Effective and cheap options include low tier Ninjas and Snipers.
Compared to Hydra Rocket Pods, Laser Cannon is better at hitting single targets and is overall cheaper. It also has the option to also get Powerful Darts to pierce through more bloons per shot while still being quite accurate overall, and has the benefit of being able to be upgraded to Plasma Accelerator.