Spells have a low drop rate so you'll need to kill her several times a to acquire a spell let alone the specific spell you need. If you're in a great hurry for the spells then I'd recommend crafting. The most efficient way of doing so is by using Evil Magma Peas and King Parsley for Reagents. While you wait for the plants to grow you can try and farm the dungeon a few more times maybe you'll get lucky!
