What are the specific rules and mechanics surrounding the powerful card Drach'nyen in Magic: The Gathering?

Drach'nyen is a powerful card in Magic: The Gathering that has specific rules and mechanics. When Drach'nyen enters the battlefield, it can deal damage to any target equal to the number of cards in your hand. Additionally, if Drach'nyen would be put into a graveyard from anywhere, you can exile it instead. This allows you to potentially reuse the card in future turns.