Thanks for all the resource providers.
Sites and softwares:
A useful site of game resources: opengameart.org/
A comprehensive site of Blizzard game resources: https://www.hiveworkshop.com/
A site for font resources: http://font.chinaz.com/
A convenient online picture editor: http://www.uupoop.com/
A convenient online video convertor: https://ezgif.com/
A powerful screen recorder, ApowerREC by Apowersoft
Warcraft3 worldeditor by Blizzard Entertainment
Pictures, textures, models:
Flasks and potions: hjm-flasks.png by Hansjörg Malthaner from http://opengameart.org/users/varkalandar
Catherine's handwriting: harabarahand from http://font.chinaz.com
Pictures such as parchment texture, fireflies, light, etc.: from internet including(but not only) Dreamstime.com, firstlook entertainment, Paixin, 视觉中国 (please forgive the roughness here...)
Some ideas and expressions: inspired by some zhihu users.