Eruption (噴火, Funka) is Ike's neutral special move in Super Smash Bros. Brawl. Similar to Roy's Flare Blade in function, Ike lifts his sword, Ragnell, and then plunges it downward in front of him which then explodes in a burst of flames. It can be charged for up to 5 seconds, and the fire greatly increases its range and knockback. The knockback caused by this move is mostly vertical when it isn't charged fully and becomes more horizontal when it is. Graphically, it resembles the animation of the Bolganone spell in Fire Emblem: Path of Radiance. Like most of Ike's moves, it is powerful enough that charging is not required for it to be effective. The flames reach high up, so there is a large vertical hitbox as well. There are also smaller hitboxes below, far in front of, and behind Ike.
 Description from the Instruction Booklet
Call forth a column of flame. Don't charge it too long, or you'll strike automatically and damage yourself.
 Reverse Eruption
In Brawl, most neutral special moves can be reversed by tapping the control stick in the opposite direction a few frames after the neutral special move has been activated. Ike's Eruption can be reversed with no increase to damage, knockback and has no reverse animation, this makes reversing only useful if it is used to attack behind Ike. It is interesting to note that when in Ike's running animation and activating a reverse Eruption, Ike will turn around and slide forward a little while charging or releasing the attack, this is probably because the running momentum has switched direction with Ike since there is no animation for the reverse Eruption and pushed him forward as if he didn't turn around at all.
Eruption has 9 stages of power, 8 charging up stages and the fully-charge stage. A fully charged Eruption has a larger hitbox and a horizontal trajectory while dealing 10% to Ike. Ike will start flashing red once he reaches stage 7.
A stage 8 Eruption is Ike's most powerful attack, and it is strong enough to OHKO the majority of the characters in Brawl under usual circumstances. For example, only Bowser, Donkey Kong, Snake, King Dedede, Ganondorf, Ike, Captain Falcon, and Link can survive a stage 8 Eruption on Final Destination at 0% without DI or Momentum Canceling. The timing for a stage 8 Eruption is very precise however, as the player must release the special button the frame just before the attack becomes fully charged. If done too soon, it will just be at stage 7. If done too late, Ike will release Eruption as fully charged. This makes Eruption the only OHKO attack among character attacks in Brawl that is not a Final Smash nor a special move that relies on counter scaling (such as Oil Panic).
 Video demonstration
The following is a video demonstration of the nine stages of Eruption.
 Other properties
This attack, like Ike's Aether, possesses launch resistance. The moment that the special button is released to the point where the sword hits the ground are launch resistant frames. As Ike is particularly susceptible to juggling due to his high weight and falling speed, the launch resistance frames can be useful for defending against it.
A fully charged Eruption can break any character's shield, provided that it was not a perfect shield. It can also be a meteor smash when sweetspotted on the tip at the very end of the hitbox, but it's quite a weak spike that only works on grounded opponents, and it's impracticality makes it rarely used on purpose (if at all) in competitive play.