Dax, Icon of Death

When Dax enters the battlefield each opponent
puts the top three cards of their library into their graveyard.
Whenever a creature is put into a graveyard from
a library exile it and create 0/1 token that's a
copy of that creature, its a zombie in addition to
its other creature types.
When Dax leaves the battlefield put all
creatures from exile into the graveyard.