The card effect descriptions below have been pulled from the Gameboy DS game Yu-Gi-OH! Nightmare Trubador. I believe that they are the most official effect descriptions to date for the Egyptian God Cards. You can download a PDF version of these descriptions with the button at the bottom of the page.
The heavens twist and thunder roars, signaling the coming of this ancient creature, and the dawn of true power.
EFFECT: You must offer 3 Tributes to Tribute Summon this card. The ATK and DEF of this card becomes the number of cards in your Hand x 1000. When this card is Special Summoned, it is sent to the Graveyard during the End Phase. While this card is face-up on the Field, it cannot be targeted by Spells, Traps, or Monsters that designate a target. Additionally, when your opponent successfully Summons or Flip Summons a Monster with 2000 DEF or less, it destroys that Monster.
The decent of this mighty creature shall be heralded by burning winds and twisted land. And with the coming of this horror, those who draw breath shall know the true meaning of eternal slumber.
EFFECT: You must offer 3 Tributes to Tribute Summon this card. When this card is Special Summoned, it is sent to the Graveyard during the End Phase. While this card is face-up on the Field, it cannot be targeted by Spells, Traps, or Monsters that designate a target. By offering 2 Monsters on your Field as Tributes, all Monsters on your opponent's Field are Destroyed.
Spirits sing of a powerful creature that rules over all that is mystic.
EFFECT: You must offer 3 Tributes to Tribute Sommon this card. The ATK and DEF of this card becomes the sum of the respective ATK and DEF values of the Tributes. When this card is Special Summoned, it is sent to the Graveyard during the End Phase. While this card is face-up on the Field, it cannot be targeted by Spells, Traps or Monsters that designate a target. When this card is successfully Special Summoned, you may activate one of the following effects: • Pay 1000 Life Points to destroy one monster on the Field and remove it from the game. • Pay all but 1 Life Points, and increase ATK and DEF by the amount of Life Points paid.
