I make only 1 ou 2 mission with new Ember. She would be barly good without this damn insane drain ramp up that entirely prenvent us to use her 2.
For her 1. I don't use fireball (and all of thoses kind of power, like Freeze) because i can't have a direct access to the power (not enough button on my mouse, i have to use mouse roll to switch between powers). And weapons make more damage. So, it's more a personnal preference.
For her 2. Good if we could rely on DR it provide. But not fully useable because of the energie drain. The meter should display the current step of increase, it would be easier to make the math to regulate it during the fight.
For her 3. Usefull against Greenir, panic button against Corpus and Infested. But it seem bugged since some mobs doesn't be affected by it. Alas, for now, it's mainly used to reduce heat meter and avoid the energie drain. Maybe should you make it replenish energie (and/or heal her if energy is full) and make his augment remove armor. It would be more universal and make more sens with his cost and the meter's drain wich justifie his use.
For her 4. Should be a 360° power. And why mobs in flame have not heat statut on them ?? And why have you named it Inferno since there is meteors that fall from sky and not flame from hell ?? Something like Skyferno would be more appropriate.
The interactions between the meter and her other powers are not combo that amplify effects, like others predefined interaction of the others frame, but just prevent us to be too powerful. And a DR foolishly upping and downing like a rollercoaster is not suffiscient to force us to depend of theses interactions. In this state, she's just a low/mid level fast nuker frame.
If i could make some suggestions.
For the meter, you may use it to regulate the effect of her power instead of the use of her power. Why don't you make it part of her passive ? For exemple, it may be représentative of the percentage of mobs under ignite state in affinity range ?
Instead of making damage, her ult may be use to combust mobs in range that are not already combusted. Combust is a special state including ignite state but interrupt mob's action, with panic animation is 4s depending on duration mods. Augment may reduce/remove armor.
Then her 1 make damage to combusted mobs relative to the mobs life (~5% depending of strengh) in function of the meter (0%-100% of the ~5%).
Her 3 vacuum heat from combusted mobs in range (removing the combust/ignite state) and the heat may be converted in health/energy depending of the meter when the power was casted then splited between allies in range. Augment may temporarie give a buff to allies touch by the wave.
Instead of raw damage reduction, her 2 may simply deflect bullets and reduce precision of mobs, a bit like Zephyr.
She can be a great [DPS-mob killer] frame without being a map nuker (interaction between1 and 4), support allies by healling/energizing (interaction between 3 and 4), buffing allies (1 and 3 augment), weaken mobs (4 augment), sharing deflecting (2 augment) and provide a descent CC (3+4).