Gran Rey Cero
Gran Rey Cero ((王虚の閃光, (グラン・レイ・セロ), guran rei sero; Spanish for "Grand King Zero", Japanese for "Royal Hollow Flash") is a powerful and potent variation of Cero, it is only permitted that Espada level Hollow are use it.
 DescriptionZanpakutō and mixing their blood with a normal Cero. The resultant force is far greater in force, power, size, and speed, it also changes colour to suit the colour of the Arrancar's Spiritual Energy. This variant is far more powerful than a normal Cero and is capable of disturbing the fabric of space. When released it makes a razor like
Because of it's power Ulquiorra Cifer stated that the use of the Gran Rey Cero is part of only 2 rules Espada have to follow. The first is that Espada number 4 and over cannot release their Zanpakutō underneath the dome of Las Noches, and the other is that no Espada is permitted to using the Gran Rey Cero within Las Noches, as the sheer power of the Cero would obliterate the building.
As of late, Grimmjow Jaegerjaques is the only one shown to use this technique. Both Ulquiorra and Grimmjow call it "The Espada's Cero" so it is assumed that the other current Espada level Arrancar are also able to use it. Although said to take the colour of the Arrancar's Riatsu it is still undetermined if that is true or if they are all blue in colour.