Tips and Tricks
You can earn screams directly from your captive princes, you can lay down scream machines that will give you additional currency, and collect screams from certain enemies that are defeated in your castle.
Use auto-traps they will activate whenever an enemy is in range.
You first move should nearly always be to install a scream generator - two if you can get away with it. It'll pay off throughout the round.
Try placing spear guns near ladders to cover multiple floors.
The acid dripper, but it can cause loads of damage on levels with lots of ladders.
Don't go crazy on the ground floor since a lot of enemies won't even pass through it.