Can't that thing be crafted before hardmode ? I mean the boss summoner , all the materials i think can be collected pre-hardmode , also what about expert mode ? Also i think it should have 15 defence instead of 10 . I support the idea !
Also another idea for a new drop , glowstick gun , uses glowsticks as ammo , when they hit something they just remain in the background till they disappear , very fast use time (14) , 33 damage , average knockback (6) , critical chance : 4 . Consider it as an updated version of the sandgun , it uses glowsticks as ammo !