Nekri Thalassa the Mirrorless

When Nekri Thalassa the Mirrorless enters the battlefield choose one :
· Create a Token that is a Copy of a Creature in an Opponents Graveyard, except it's a 4/4 Black Horror Token with " At the beginning of your Upkeep sacrafice another Creature. If you can't you put X Crads from your Library in to your Graveyard , where X is the converted Mana Cost of the copied Creature."
· Create a Token that is a Copy of a Creature in your Graveyard, except it's a Illusion with Echo {u/b}{u/b} and " If this C