Converse with Spirits

At the beginning of your upkeep, you may mill X
where X is equal to the number of creatures in
your graveyard. Then you may choose target
creature in your graveyard with mana value X or
less, you may cast that creature from your
graveyard until the end of turn, if you do it
costs {x} mana less.
" There is much to learn from the dead, it is a pity
so many mages stray away from necromancy. "