Ember's 2 doesn't use energy at all. Unless... Unless you let your meter hit the cap, then it uses a bunch. Originally it was going to go "boom" in a big radial explosion and use all your energy if you let it do that, so be thankful DE changed their mind and went with a stiff energy drain instead.
You need to mix using your 3 in to keep your meter under control. Use your 4 to get the meter filling fast, then use your 3 just enough to keep it mostly under control. Basically you juggle your energy and heat all the time, it is a very active play style.
You say her 3 needs to reset the rate, which tells me you don't use it enough. It does reset the rate by about the same amount her 4 boosts it. If it is filling too fast, cast 3 again to slow it down.
Quick question: have you playtested, or are you just going by the patchnotes? Because I was running an efficiency/duration build with Energy Siphon, Arcane Energize, Primed Flow, Hunter Adrenaline, and Zenurik tree active and would still go through a full tank in less than a minute despite quintuple-dipping regen. The amount of energy you need to spend on 3 to keep your 2 meter down if you're casting 4 at all is ruinous. It was bad to the point that I could double-tap 3 and the 2 meter build rate was so high that it was back to 90% in two or three seconds, and continued to build at that rate until deactivated.
Here's why it's a problem: two casts of Inferno require three casts of Fire Blast to neutralize the build rate increase. Pre-efficiency that's 425 energy to press 4 twice with no negative effects on your 2. If you're trying to kill things with the former while maintaining survivability, you get caught in an energy drain death spiral. The correct answer to this problem shouldn't be "Don't cast Inferno".
Kuva liches appear to have migrated heavily from the original concept and now exist mostly to force you to grind so that you can grind so that you can grind.
i thought that was what plenty of updates were
But yeah, don't know how to actually do stuff with the Liches at the moment. Again, maybe it's something really obvious that I'm missing.
Oh no, it's bad.
1. Grind random Grineer starchart missions to get your lich started without randoms gibbing it before you activate it (it's the glowing red one with an icon over it).
2. Realize you've made a mistake as red covers the starchart, important loot gets stolen, and you see that the "reward" for hours of grind will be a 22% magnetic Kraken.
3. Grind kuva siphons for that 30% chance of getting a relic. Watch the relic get stolen. Repeat.
4. Grind fissures for traces to rad the new relics.
5. Grind your choice of survival or rescue with the new relics. Get 15 adapter BPs/kuva/ambers/riven shards for every one mod. Wish you'd done this part before activating the lich. Repeat until you have one of each.
6. Grind thrall missions for no rewards except tiny amounts of progress for the extra grind layer disguised as a puzzle, or until you get lucky with your guesses. It isn't going to be the latter.
7. Grind for lich encounters so that you can guess which order the set you need has to be in. Never get any because other people don't kill their own so yours can't spawn.
8. Finally kill the damn thing. Get your choice between a probably trash weapon that you need to forma 5 times for mastery or a specter that doesn't do much, almost never shows up, and sometimes starts trying to kill you while invulnerable.
9. Accidentally start another one ten minutes later.