The Green Lanters and the rest of the universe are probably going to be butt raped. Anyway:
Tathamet The Prime Evil
Tathamet is a seven-headed dragon of pure evil and all that is vile. It was known as the Prime Evil and was created as a cast off of all the dark attributes within Anu long before Sanctuary came into existence.
Tathamet was all the evil in the existence cast away from the body of Anu (God). They battled until each other were defeated and were teleported to a higher plane of existence. The body of Tathamet gaved birth to the Realms of hell and all demons. Tyrael said that Prime Evil Diablo was just a very very very very very veryyyyyyyy small portion of the true Tathamet, and if he was able to resurrect him, he would just own everybody. Diablo Prime Evil broke Solarian, Imperius Super Mjornil with his touch and destroyed the Diamond Gates with his breath. This just give an idea of how powerful Tathamet is.
Solarion, the Spear of Valor, was the weapon of choice of the archangel Imperius. According to the legend, the weapon was forged by Imperius in the heart of a dying star. It has been said to be an extension of his own will, powerful enough to sunder Hell's mightest ramparts with a single strike. During one of Imperius's invasions of Hell, it is written that Solarion felled so many demons that rivers of blood flowed throughout the realms of the Great Evils
Imperius was know to defeat The Nephalem (god like beings) just with his will.