From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
The Makankosappo (魔貫光殺砲, Makankōsappō; FUNimation "Special Beam Cannon"; Literally meaning "Demon Consistent Light Killing Cannon") is an energy wave attack and Piccolo's signature attack. The technique is a very powerful laser beam created by Piccolo in order to destroy his then arch-enemy, Son Goku.
The user touches their index and middle fingers of one hand to their forehead and charges enough energy to attack. Its speed changes relative to the user's battle power. They then extend their fingers forward and shout the name of the attack, firing two thin Ki beams from the fingers. One beam remains straight while the other beam coils around the straight beam. The resulting beam is quite powerful and drills through most targets, exploding on the targets it cannot. It can also be used with only one arm (as when Piccolo used it for the first time).
The main disadvantage of the attack is the time required to build up enough energy for the focused burst, however, with enough concentration, the user can bypass this problem. It is the first technique in the series to be referred to as being faster than light, as Piccolo reasons that Raditz has to be "faster than the speed of light" to evade it.
 Dragon Ball Z
 Vegeta Saga
Piccolo first used the Special Beam Cannon in his battle against Raditz. The first time it was used, Raditz dodged and was only singed by it. The second time was a direct hit, killing both him and Son Goku in one shot. During his training with Piccolo, Gohan transformed into a Great Ape, therefore Piccolo used the Special Beam Cannon to destroy the spaceship Goku had used to come to Earth because it had been was projecting an image of a full moon in the sky, which caused the Great Ape transformation. Piccolo used an attack with a similar appearance in his battle against Nappa, though he fired it differently (both hands fully outstretched) and did not have to charge it up. He used this same move while training with Gohan, only it was blue.
 Namek Saga
 Garlic Jr. Saga
Piccolo trained with several copies of himself in "The Heavens Tremble". All of the copies fired the Makankosappo at the original Piccolo, only to have it blown away.
 Imperfect Cell Saga
Future Cell used this attack in his first fight against Piccolo, but the blast was deflected by Piccolo.
 Cell Games Saga
 Fusion Saga
Super Boo (Goten, Trunks, and Piccolo absorbed) used this attack in his fight against Gohan.
In the non-manga uses of this move, the charging time was much shorter, though the resulting blast was seemingly less powerful.
 Dragon Ball GT
Piccolo used this attack in his fight against Gohan Baby to no avail.
 Dragon Ball Z: The Tree of Might
 Dragon Ball Z: Cooler's Revenge
 Dragon Ball Z: Bojack Unbound
 Dragon Ball: Ossu! Kaette Kita Son Gokū to Nakama-tachi!!
Piccolo used this attack in Dragon Ball: Ossu! Kaette Kita Son Gokū to Nakama-tachi!!.
 Video games
 Dragon Ball Z: Budokai Tenkaichi 3
 Character meaning
- 魔 (ma) = demon/devil/evil
- 貫 (kan) = penetrate/pierce
- 光 (kō) = light/ray/beam
- 殺 (sa/satsu) = kill
- 砲 (hō/pō) = cannon/gun
- The technique is colored purple instead of yellow in the Budokai video game series. This coloration is also present in Dragon Ball Z: Burst Limit and Super Dragon Ball Z. Cell Junior can use this attack and his version is colored blue in Dragon Ball Z: Sūpā Butōden 2.
- This move has actually only killed three people, Goku, Raditz, and Salza, even though it was used many times in the series and films.
- During the battle against Raditz (Dragon Ball Z Kai), in a flashback where Piccolo fires the Special Beam Cannon, Piccolo yells "Makankosappo!" instead of "Special Beam Cannon!" as in the actual fight in the previous episode.
- When Piccolo fires the Special Beam Cannon, its color is green in Dragon Ball Z: Supersonic Warriors 2.
- Because this skill is chosen in combat so much, one can assume that it is among the best techniques to use.