my English is poor. I think I can't really understand these skills and how they work together.
Is there any build I can copy, or one kind of the potion can buy a lot then"pay to win"?
Get invisibility, mana shield, summon skeleton, demon, rat talismans, drain mana. In the buff screen, cast invisibility on yourself and summon everything you can. In battle, simply heal yourself and don't attack. The fairies won't be able to attack you and will waste mana on summons. Then finish them off.