19th level of the Eyrie of the Avian King (Tower in Sandperch Desert).
Opposing Army Edit
Strategy Guide Edit
Try placing Slow Towers at the beginning and if you have a Well of Souls then place that next. Clarion Call is useful too and Sapphira is great, especially against the Bluefeather Bombardiers. Use Bolas for the rest of the spots:
I have Level 2 Well of Souls, Level 4 Bolas and Level 6 Slowdown Tower.