User blog comment:RaijinSenshi19/Omni Lord Hierarchy Decklists - Part 5: The Setting Sun/@comment-24965906-20160308203148/@comment-6102960-20160309065814

As I said, Harpy is somewhat a placeholder. I use her with Sylph, then sack her with Elizabeth, effectively trading 1 life for a full field that I want.

But her 2 spots can be changed with anything you want, be it Grail, Weiterstadt, or anything you wish for, really.