Deluded Nymph

When Deluded Nymph enters the battlefield, if it had a -1/-1 counter on it, you may sacrifice a creature. If you do, remove a -1/-1 counter from it.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)
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"You're mine now, for ever and ever."