doctorbadwolf
Heretic of The Seventh Circle
OkayWhile that is a tone explicitly gone for in the 3.5 core book and executed in some of the supplements with lots of low level important NPCs (The Lord of Blades is a CR 12) there are high CR stuff throughout the setting. Big ones include:
The Lords of Dust. Demon Lord level archfiend rakshasa.
The Dragons. Flipping through Dragons of Argonnesan I get a CR 36 lawful evil great wyrm silver dragon statted out, The Prophecy Incarnate.
The Quori. Secrets of Sarlona has a CR 20 Kallarq Quori statted out.