The Zanku Hadoken (斬空波動拳, Zankuu Hadoken, "Slashing Sky Surge Fist") is a version of the Gohadoken that is commonly associated with Akuma.
In its crossover appearances, Ken can use the move as well, and in X-Men vs. Street Fighter, Rogue can also use this technique by using her Stolen Power special attack on Akuma.
It is executed the same as a regular Hadoken, albeit in midair. The user thrusts their hands and fires an airborne Hadoken, angled down.
The angle is usually about 45° downwards, and the speed at which the fireballs fall depends on the strength of the punch button pressed, with the weakest going slower, and the stronger falling faster.
The EX Special version introduced in the Street Fighter IV series allows Akuma to throw two fireballs instead of one, which is an ability that he has naturally when he is at his most powerful.
The Zanku Hadoken is great for stopping close-range counters while in the air and assaulting grounded foes.