Empress of Light – Terraria: Journey’s End
Pro-tip: Don’t fight Empress of Light during the day. Added in Update 1.4, she can appear after defeating Plantera and one-shot kill you in the daytime. Fighting at night is the best option but you’ll need to deal with her Prismatic Bolts, dash attacks, Ethereal Lance (read: Waves of swords) and much, much more. She also has great mobility and 70,000 HP (which can go up to 124,950 HP in Master Mode) so you better go in with your best possible gear.