Shadow of Asgard

Necro {1}{b}(If a creature card with {1}{b} in its
mana cost went to the graveyard from anywhere this
turn, this spell costs {1}{b} less to cast.)
When Shadow of Asgard enters play, pay X life.
Other creatures gets -X/-X until end of turn. If a
non-token creature goes to the graveyard this
turn, its controller creates a black 1/1 Wraith
creature token at the end of their next turn.
Shadow of Asgard gets +X/+X, where X is equal
to the number of Wraiths in play.