Laser Towers have a low range and attack a large number of monsters at the same time, just like Cannon Towers, but stronger. Attack them using Teratorn or D.A.V.E.s with Rockets level 2, so they won't take damage.
Do not place a large number of monsters (like Pokeys) near a Laser Tower, because most of them will die in the first attack.
Also, fast monsters like Eye-ra and Bolt can outrun the Laser when they are walking, making the tower deal no damage. So, its good to use Eye-ras or Bolts to "annoy" the tower without getting any damage. Bolts are more likely to teleport without triggering the tower, though.
Due to their splash damage properties, the damage Laser Towers do should be maximized by funneling attacking monsters into groups. This can be done with excellent use of blocks to form walls and mazes to force attackers to path into the relatively short range of the tower. Another more unorthodox method is to use another tower as bait, so attacking monsters will clump around the tower - and after it is destroyed, the monsters are ripe for Laser Towers and Booby Traps.
Always put a Sniper, Tesla, or even a Aerial Defense Tower next to a Laser Tower, so it will be protected from ranged atacks. The best way to use Laser Tower is to defend your yard from Dreadnaut Tribe's Brain attack. If you know the side of the yard where they will attack from, then place an empty Resource Harvester on that side. Place two Laser Towers in front of it. It's best to have at least level 4 Laser Towers. Click "I'm Ready Now" and see the Brains flock to the Laser Tower to be killed like moths to a flame. It is still necessary, however, to have other towers protect the Laser Towers.
Do a runner block and put a Laser Towers on each side and see a mass destruction of monsters. It is very useful for your defenses.
It is a very good defense against Dreadnaut Tribe attacks, because they use lots of Brains - and they run together, allowing the Laser Tower to pick them off with ease.