For Ember, your priorities should be:
Range (it's really her best defense)
Power
Duration/Efficiency (same diff, really)
Dial back on your defensive mods. Try to learn to function with just one. And Vigor is just a terrible mod.
My build:
- Growing Power for Aura
- Power Drift for Exilus
- Stretch
- Overextended
- Transient Fortitude
- Energy Conversion
- Intensify
- Fleeting Expertise
- Primed Continuity
- Vitality...or I sometimes swap out with Armored Agility...speed is also a great form of defense
A lot of people like the Firequake augment, but I can't find room for it, and I find that the normal fire procs are a fine form of CC.
With enough efficiency and duration, you can just keep World on Fire on at all times. You'll want to proc both Growing Power and Energy Conversion before activating it for the power bump. And then you just drop Accellerant every now and then like it's your ultimate and watch faces melt.
I think the mod system in Warframe is the best "skill tree" of any game I've ever played.