Most of her is cool, not crazy. I like the reverse Martyr, that's funny. Wish it worked when Cask Imps blew up, but that'd be a bit much even for an unofficial model. Cataclysm is the same, nice get-out-of-jail spell that is rarely cast, Dessolution is a good purification, Hellbound is probably her worst spell (anything within 5" has a good shot at killing her anyways), and her feat is her feat.
Then there's the bonkers stuff. 1) Sac Pawn [Grymkin]. Ummmmm....yeah. Crabbits can now shield guard until dead. This makes Harbinger basically unkillable at range, which is one of her biggest weaknesses.
2) Falter Courage. I'm sorry, a spammable, non-upkeep spell that steals an attack die? Crazy good.
3) Hesitation of Faith. Probably less used than Falter Courage, as it'll only have 1-2 turns of relevance, but still. -2 SPD to any charge within 20" of her is really, really strong.