At the classic store at the top of the desert, you need to buy one of each coil type. There are three different types, speed, jump, and health if not all of them are there just wait for the shop to reset. Once you have those three get a meteor core which has a 1/3 chance to drop from meteor and bring it to uncertainty cave. There hold the core up to a mysterious mushroom and have the mushroom shoot one of its spores at the coil. If done right the core should change color. I forgot where in uncertainty cave but there is a wall that needs dynamite to blow up. Behind the wall is a pond with pink bamboo. Drop the three coils and the core into the water next to each other and they should slowly fade and create the fusion coil which is the coil I'm using. When held you gain speed jump boost and life regen.
