One of the 3 mechanical bosses
A sample of hard mode inventory
New stations from V1.3
Hallowed Armor, Demon Wings, and Frost Staff
Skeletron's Dungeon found in the overworld
A small sample of the functional items attainable
Witch Doctor and Wizard
Ash Biome in the Underworld with a Demon
Ballista and Catapult turrets in a Goblin encampment
The Crystal vile shard and the Clinger staff
New villagers including the Merchant, Guide, and Goblin Tinkerer
Found just below the surface
The 3 special biome specific mimics
The Brain of Cthulhu inside of a Crimson cave
The Corruption biome found in the overworld with Eater of Souls mobs
Wyvern
The Hallow biome with a unicorn and a pixie