Gestalt Psionic Devil

[Effero]

This board has helped me out on my last character build so I thought I would post a new theoretical gestalt build and see what people thought.

Race: Unholy Scion Kalashtar
Level 1: Psion 1/Planar Ranger 1
Level 2: Psion 2/Planar Ranger 2
Level 3: Psion 3/Planar Ranger 3
Level 4: Psion 4/Planar Ranger 4
Level 5: Psion 5/Thrallherd 1
Level 6: Psion 6/Fiend of Corruption 1
Level 7: Psion 7/Fiend of Corruption 2
Level 8: Psion 8/Fiend of Corruption 3
Level 9: Psion 9/Fiend of Corruption 4
Level 10: Psion 10/Fiend of Corruption 5
Level 11: Psion 11/Fiend of Corruption 6
Level 12: Planar Ranger 5/Thrallherd 2
Level 13: Planar Ranger 6/Thrallherd 3
Level 14: Planar Ranger 7/Thrallherd 4
Level 15: Planar Ranger 8/Thrallherd 5
Level 16: Planar Ranger 9/Thrallherd 6
Level 17: Planar Ranger 10/Thrallherd 7
Level 18: Planar Ranger 11/Thrallherd 8
Level 19: Planar Ranger 12/Thrallherd 9
Level 20: Psion 12/Thrallherd 10