Nova Strike

Nova Strike (ノヴァ・ストライク) is the Giga Attack of the Ultimate Armor and the Fourth Armor. X first surrounds his body with immense energy, then performs an invincible flying tackle that plows through (and destroys) enemies almost effortlessly.

In Mega Man X4-Mega Man X6, X can use this attack infinitely (except in the Fourth Armor's version, where energy needs to be refilled like normal Giga Attacks). In Mega Man X8, the Nova Strike is modified along with the Ultimate Armor. It now has Weapon Energy (WE); however, it recharges over a small period of time (a matter of seconds, in fact). The only downside to this is that it prevents the Nova Strike from being used over and over. To compensate for this added weakness, the Nova Strike's travelling distance is increased, and it can now destroy all bosses in only two hits (the first hit depletes all of the boss's energy but one unit, triggering the boss's overdrive, which is always mandatory).

In Mega Man X: Command Mission, X's Ultimate Armor is much different from the previous versions, and his Nova Strike is a series of explosions and powerful amounts of damage done to the enemy. It is one of the two strongest Hyper Modes of the game, along with Zero's exclusive Absolute Zero.

Other appearances
X also uses the Nova Strike in the crossover Project X Zone. In the Mega Man Zero series, one of the attacks from Copy X's first form is the Nova Strike.