The Undead Menagerie

When The Undead Menagerie enters the battlefield, exile X creatures cards from your graveyard.
The Undead Menagerie has the activated abilities
of all creature cards exiled by this card.
The Undead Menagerie power and toughness is
equal to X. X is the total power and toughness of creatures of exiled by it.
We all will die to give it strength