techniques: double bomb jump
Standard bomb jump involving 3 bombs. Use a bomb, and just as it explodes, use another. At the peak of the ascent from the first one, place the third. Remain close as the bombs explode to be launched two levels high.
Unlike the other bomb jumps, dbjs can't be combined with bs jumps; even if you get the instant unmorph, the game doesn't let you jump when you revert to human form. This and having space jump for the entire game makes their use in MP3 limited. In all honesty, you're better off with the 2bj, which is compatible with bs jumps and barely harder to learn.
To see this move in action, try the link below.
Double bomb jump (sample video)