Frost Tower

Frost Tower (フロストタワー Furosuto Tawā?) is the Special Weapon that Mega Man X obtains from defeating Frost Walrus in Mega Man X4. When equipped with this weapon, X generates a large, jagged ice block that acts as a shield for him before disappearing. The Frost Tower can protect X from enemies by damaging or destroying them if they make contact with it; projectiles however will just go through the ice block and can potentially hit X. Because the Frost Tower does not act as a solid obstacle for X, the player can move him outside of the block or can leave him standing while "inside" it, protecting him from enemy contact. When used in the air, the Frost Tower will fall straight down and hit the ground. Any enemies directly below X can be damaged with this method. When the Frost Tower disappears, it explodes into many shards of ice, but the shards however are more of a visual effect and do not inflict damage. Only one Frost Tower can be on the screen at a time.
When charged, X sends down gigantic ice shards that fall down the screen. There are four waves to this attack and the amount of shards that fall down is equal to the number of the wave (first wave has one icicle, the second has two, etc.), resulting in a total of ten shards used for the attack. This covers a very wide range and can do a decent amount of damage to any enemies on the screen. The player can control X the moment after the first wave begins.
This weapon is the primary weakness for Jet Stingray and Colonel, though only Stingray will have a weakness reaction to this weapon.