I am going to tell you how to make a boss battle I havn't actually made one that attacks you but I will in the future a boss can be made by making something withe redstone going through it attached to minecarts on detector rails (destroy all the minecarts to win) if you want your boss to blow up place a block with a redstone torch on and attach the redstone from the boss to the top make sure there's no contact with the redstone torch other wise when you kill the boss it will cause a repeater next to the redstone torch place TNT make sure the TNT is only connected to the redstone torch then spread the TNT throughout your boss without it getting set off by redstone important note: when placing TNT make sure the boss is alive (minecarts are in place) then when you kill the boss it should blow up there is a video showing a harmless snake boss that's easy to make and kill on my YouTube channel (Prionzombie).