The Sphere of the Sphinx is a weaker version of the Big Bang Attack developed by Ed (who apparently had never seen the Big Bang attak) . The attack is one of Ed's signature moves. It is a giant orb of energy that (according to Ed) has the ancient power of the Egyptians. Although this attack has been replaced by the Zappity Zap Zap as Ed's signature attack, Ed has used it numerous times, and proved to be his Ultimate in the Heritage Saga. In later episodes it is not as prevalent.
Like the Big Bang Attack, this is is a energy attack charged by the user outstretching one hand forward and is fired the same way. This attack can cause serious damage to the opponent and can be multiplied to cause even more damage, which is called Storm of the Sphinx.
There is another variation of the move called Sphere of the Sphinx - Double Fire, which, as its name implies, fires off two Spheres of the Sphinx. This move is similar to the Twin Dragon Shot (The Kamehameha variation that Goku used in his fight against Frieza at half power.) in some aspects. The main difference is that Ed uses only one hand to generate the shots, whereas the Twin Dragon Shot requires both hands. In Episode 50, Ed can now shoot the Double Fire variation with both hands.
This attack came into conception in Universe M-9314 (by TheMelon93), and later made its animated debut in Episode 7 of the Animated Series.