Mobs:

• Added Penumbra 
• Added Tundra Ghoul (Mist Ghoul replacement)
• All ghost entites (Tormented Soul and Tundra Ghoul) now require you to have Soul Tools to deal significant damage to them.
• Tormented Soul texture updated

Biomes:

• Added Soul Plains (replacement for Cursed Plains)
• Added Haunted Tundra
• Added Forgotten Forest (trees are placeholder)
• Added Sculk Forest (trees are placeholder)
• Cursed Plains no longer spawn

Structures:

• Added a Cursed Realm Portal structure (can find the Soul Smithing Upgrade in the chest)
• Added Ruined Grimstone Buildings
• Added Grimstone Towers

Blocks:

• Added Grimstone
• Added Deepstone
• Added Forgotten Wood type
• Added Grimstone Iron Ore