The Nightmare looks like the 'Nightmare' from Five Nights at Freddy's 4 in the Position like the Moon Lord is and has two forms. The second form has the same stats like the first, but it doesn't looks like the first, it looks like the Endoskeleton from Five Nights at Freddy's 2. He'll be the very last Boss of Terraria.
He will have four arms, one head and two Eyes, who can attack you but you can attack them too.
With his arms he will punch you (like the BIG Monster in Star Wars The Force Unleashed 2).
He can open his head, where Freddles (10-100) will come out.
He will have a Laser in one eye and a bomb launcher in the other.
Arms: 950 000 every
Head: 1 250 000
Freddles: 250 every
Eyes: 475 000 every
Summoning and Drops:Edit
Can be summoned at: Night
Appears: At the End (87%+) of Wave 7 of the 1987 Legion (Sometimes (25%) appears when you play at 1-9AM 87+ Minutes (1h 27m+)) and you haven't died. OR: By using the item 'LAST NIGHTMARE'.
Drops: 250 Nightmare Ore (100%), 1 THE REAL SCREAM (0.50%(1 987 198 719 871 987 Damage(Strongest Weapon in Terraria))), 1 Bite Victim (25%(Summons Pet Nightmare (1987 Damage) who will fight for you)), The new and shiny (100%(Summons the Toy Animatronics)), THE BIG SUPRISE (19.87%)9 999 999 999 Damage(Sword what can shoot projectiles like the Terra Blade))
Hope you like it!