Skuld, Guide of the Fallen

Flying, Indestructible
Skuld, Guide of the Fallen enters the battlefield
with 10 Ragnarok counters on it.
Whenever a legendary creature dies, remove a Ragnarok counter from Skuld, Guide of the
Falllen, and then exile that creature. When Skuld,
Guide of the Fallen has no Ragnarok counters on
it, return all creatures exiled this way to the battlefield under your control.