Archvale

The Fallen Pharaoh can be found in the Desert Biome (Dustcrag) within the Temple (Tomb of Kings). Once inside the temple you'll have to clear numerous rooms and find two stone tablets that open her tomb door.

Once the inner door is opened you'll encounter one mini boss room and a fountain before the final boss room. Do your best to nuke her down while avoiding her projectiles. The flaming braziers defend her from taking damage, try to attack her without hitting the braziers.