Mechanical bosses

Mechanical Boss is a term which refers to any of the three Hardmode bosses that can be summoned by "Mechanical" items. Once Hardmode begins, they will begin to spawn randomly until each individual one is defeated at least once.After defeating one hardmode boss a Solar Eclipse can happen in a day with 4% chance (1 in 25). After all three Mechanical bosses have been slain at least once each, Plantera's Bulb will begin to grow.