It's a beam of chaos energy, it's focused out of the user's hands (like a kamehameha) It can be charged to very destructive levels of power. If charged to the max, it becomes a Chaos Megalaser, which can destroy planets.
Vuxo the Hedgehog and his powered-down form Star can use Chaos Laser. However, only Vuxo can use Chaos Megalaser.
Malik the Hedgehog also has the ability to use Chaos Laser, but does not have a sufficient Chaos energy pool to use its Megalaser variant.
It was discovered by Shadow after he went back to ancient times, he attempted to learn it from the creators of chaos (Chaos himself) but, couldn't complete the training (it was too tough) so he left back to his own time.(present) Vuxo fought Shadow a little after he came in, Vuxo showed off his powers and beat Shadow with a Chaos Laser. He then during the fight with all 9 of them, used Chaos Megalaser to end the battle.
It requires an extreme amount of chaos energy to use, even the basic form of it drains energy rapidly. So it means you need to be able to use chaos powers.
The only significant variant is Vuxo's Chaos Megalaser, which requires an almost unimaginable amount of energy to control, but Vuxo, being a bad guy, decides to absorb energy from the enviroment, which is how he's able to blast his megalaser for an extreme amount of time. So long, that in fact, at this rate, he'll probably become too powerful at it and end up destroying the universe.
It's only weak point is the fact it drains energy so quickly, even Vuxo's feeding off the enviroment can't sustain it forever.
It's only drawback is that it takes so much energy, even beings made of chaos can't use it long.
It can be charged as long as the user has enough energy, meaning the stronger the user, the stronger the attack.