First of all - great game! A well-deserved 5/5.
Thanks to SimpleHarmonic for your tips on how to configure your troops! That helped a lot!
In addition, I have another easy way to get the gold faster later in the game: In levels with holy/bog towers, don't waste space to the cleanse warlock. Just go with SimpleHarmonic initial configuration and keep stunning the holy/bog tower. That way, you get more potential raids.
Great hint for slaying the final boss (played on phoenix side): just equip the forged heartstone before you turn in the forging quest. You then get to keep the stone and slaying the final enemy is a piece of cake! + if this helps