Here's a summary of their effects:
Slifer the Sky Dragon:
* Effect: This card's ATK is equal to the number of cards in your hand. It can only be Special Summoned by removing 3 "God" cards from your hand and Graveyard.
* Strengths: Can have extremely high ATK depending on your hand size.
* Weaknesses: Susceptible to hand traps and card removal. ATK can be reduced by effects that decrease hand size.
Obelisk the Tormentor:
* Effect: Cannot be destroyed by battle. This card gains 500 ATK for each monster on the field (your opponent's and your own). It can only be Special Summoned by removing 3 "God" cards from your hand and Graveyard.
* Strengths: Tough to destroy in battle and can have high ATK depending on the field's monster count.
* Weaknesses: Susceptible to card effects that destroy by other means (e.g., card destruction, banish, etc.) Can be negated by cards that prevent monsters from gaining ATK.
Ra the Winged Dragon of Destruction:
* Effect: This card's ATK is equal to the number of "God" cards in your Graveyard. It can only be Special Summoned by removing 3 "God" cards from your hand and Graveyard.
* Strengths: Can have high ATK depending on how many "God" cards you've used.
* Weaknesses: Susceptible to card removal and effects that prevent Special Summoning. Requires a dedicated strategy to utilize its full potential.
Important Notes:
* "God" Cards: These are powerful cards but require a specific strategy and deck build to utilize effectively. They are often seen as a win condition in certain decks.
* Banlist: The "God" cards have been on the Forbidden & Limited List in Yu-Gi-Oh! for a long time, restricting their usage in most formats. They are often used in casual play or certain specific formats.
* Legacy of the Duelist: The "God" cards were central to the "Ancient Egypt" storyline and are a notable part of Yu-Gi-Oh!'s history. They were very powerful in the early days of the game but have been balanced over time.
Remember that these are just the core effects. Each card has additional effects and details you can find on the official Yu-Gi-Oh! website or card database websites.