Kebero, the Infinite Scholar

Whenever a Wizard enters the battlefield under
your control, draw a card.
When Kebero, the Infinite Scholar dies, target opponent puts the top X cards of their library
into their graveyard, and you may cast any
number of instant or sorcery spells from any graveyard with total converted mana cost X or
less without paying their mana costs, where X is
the number of Wizards you control.