I thought that pre-hardmode was left out in the game as you progressed. Lunar weapons are so op but all the enemies are weak after you finished the game. I just want to share this since 1.3.5 is not yet been released. What if after you killed the Plantera, all pre-plantera enemies even the boss will be guaranteed a buff or increased in stat. For example, slimes from 100hp to 1000hp with more damage?