Kaiō-ken

Kaiō-ken (界王拳, Fist of the World King) is Goku's down special move in Super Smash Flash 2. It turns Goku into Kaiō-ken Goku who is faster and more deadly. But this transformation has it's cost. A very high one. Goku starts taking damage at 10% per second. So by 10 seconds of playing as him you'll have +100%. He gains a new side special move and a second teleportation on top of his up special move. His standard special move is toned down a bit but he becomes faster in everything else.