On The Forest Map (First Map) -
There's A Lady That Appears To Be Fixing A Roof.
1. Build Out Your Walls To Encompass The Tower She Sits Atop.
2. Paying The Coins At The Tower Starts A Blood Moon Wave.
3. After Defeating The Blood Moon Wave, If The Tower is Still Encompassed - Pay One More Coin To Get Her Down.
Achievement And New Technology Tier Unlocks.
Good Luck!