If you need a step-by-step guide, check the pinned comment on this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-YOdZ36KU5P0.html - the first few steps are a tad different from what's shown here (skills to learn, equipment, etc.), but the rest is more or less the same. Btw, to get Electro Light to spawn Vicious Metal Slimes that give massive EXP like in this video, you need to defeat Mordegon first and be in Act 3.