C4
The C4 is Solid Snake's Down B move. Snake places a C4 on the ground and may detonate it at any distance by pressing the button again, however, after (roughly) 27 seconds, it detonates automatically, without help from Snake. When Snake detonates it, he flourishes the remote detonator, and exclaims "Now!" as he presses the button. There is approximately a 1 in 6 chance that the C4 pack Snake uses will be a C3 butterfly explosive like in Metal Gear Solid 3. The attack's power remains unchanged.
When Snake says "Now!", he is attempting to detonate the C4, but this can be prevented by hitting him to interrupt the detonation. The C4 has about a 2-character explosion radius, and requires the target to be standing very close to it for the attack to be effective. It's rather easy to escape, and can also be guarded against.
C4 can be placed directly on opponents, as long as they are within Snake's reach. It acts similar to a Gooey Bomb in that it can be passed from person to person when they get near each other, but after some time it may fall off. If standing next to one, Snake can place C4 on an adjacent wall in a similar fashion to that of the Metal Gear Solid series. C4 can also be placed on teammates for a "suicide bomber" effect.
While in mid-air, C4 can be dropped and will land on the ground directly below Snake, regardless of Snake's horizontal momentum. This makes for a more tactical, subtle placement of the explosive, and can be used to place C4 without drawing attention onto oneself.
It can be used to recover your Cypher, by hitting yourself with a C4 after losing it.
Origin
C4 is a powerful plastic explosive that can be modeled like clay into various shapes. It is incapable of being detonated by anything other than the detonator itself. C4 has always been a widely used tool by Snake and is one of the weapons that is required to progress through the game.
External Links
Snake's page at the Smash Bros DOJO!! Template:Snake Special Moves