What are effects of the Yu-Gi-Oh Egyptian god cards?

Answer 1

I honestly didn't know they had this big of effects.

Slifer the Sky dragon: You must Tribute 3 monsters to Normal Summon or Set this card. The ATK and DEF of this card become the number of cards in your hand x 1000. When this card is Special Summoned from either player's Graveyard, it is returned to its controller's Graveyard at the End Phase of the turn. If this card is Special Summoned in Defense Position when your opponent has attacked with a monster, you may switch the attack target to this card. While this card is face-up on the field, it cannot be destroyed by card effects, returned to the player's hand/Deck or removed from play, its control cannot be switched, it cannot be equipped with Equip Cards, and the effects of Spells, Traps and other Monsters can only affect it until the End Phase of the turn. When your opponent Summons or Sets a monster, decrease its ATK or DEF by 2000, depending on its Battle Position; if the ATK or DEF of the summoned monster(s) is 0 after this effect resolves, destroy the monster(s).

The Winged Dragon of Ra: This card cannot be Special Summoned. You must Tribute 3 monsters to Normal Summon this card (You cannot Set this card). The Normal Summon of this card cannot be negated. When this card is Normal Summoned, the effect of Spells, Traps and Effect Monsters other than this card cannot be activated. If this card is Normal Summoned, you can pay Life Points until you have 100 Life Points left. This card gains ATK and DEF equal to the amount paid. Also, you can pay 1000 Life Points to select and destroy 1 monster on the field.

Obelisk the Tormentor: You must Tribute 3 monsters to Normal Summon this card (you cannot Set this card). The Normal Summon of this card cannot be negated. When this card is Normal Summoned, Spells, Traps, and Effect Monster effects cannot be activated. This card cannot be targeted by the effects of Spells, Traps or Effect Monsters. If this card is Special Summoned, it is sent to the Graveyard during the End Phase. You can Tribute 2 monsters to destroy all monsters your opponent controls. This card cannot declare an attack the turn this effect is activated.

Thanks to Yugioh.wikia.com for info!