the most overpowered item is probably ice spear(air+water=ice,air+wood=stick,stick+stone=spear,spear+ice=ice spear) and i also use fireball(fire+electricity=plasma,plasma+fire=fireball) because its good for moving around and has decent damage and i use fire lily(wind or water+stone=sand,sand+water=clay,wood+stone=dirt,clay+dirt=planter,planter+water=flower,flower+fire=fire lily) because it has insane damage output in closed spaces and pretty good damage in general along with not too much cooldown time
