Can you read this post? kz=7 10572372
As for learning thunder spells, I suggest Xue Jianxue, because the first two of her earth spells are all attacks, and in the later stage, her attack power of all attacks will be very weak, so the last method of thunder spells can be used.
You can let Jing Tian learn fire, earth and water, make his double-attribute magic reach five (after all, he is the protagonist), and let Xue Jian learn thunder. Zi Xuan's attack style is the weakest.
I hope I can help you ~