Complex sentence: Hurt and angry, Nessarose attempts to cast a spell from the Grimmerie to make Boq lose his heart to her, however she is not as skilled as her sister and her spell backfires, causing Boq to literally lose his heart.
Split into simpler sentences: Hurt and angry, Nessarose attempts to cast a spell from the Grimmerie to make Boq fall in love with her. However, the spell backfires, causing Boq to literally lose his heart.