**Gonna be a short post, really tired and it just popped into my head**
I think that some sort of repeatable quests should be implemented into the game for completing a tier or task... I personally think tier would be better. The idea would look something like you pick up a quest that asks you to complete a tier..all 3 tier quests available and based on personal choice...the reward would be a mist tank. This would allow people to keep playing the game without having to depend 100% on Crystal energy to do more than a run or 2 each day. This would drop the price of CE a bit but people would still need it for crafting and such so I don't think it would hurt it that bad.
Just a thought
Not that bad on paper- but! When you've got Tier3 gear, you could just continually run Tier 1 for 60 energy and get an infinite supply of mist tanks easy.
So they would have to limit it based on your gear, and set a limit of how many you could get in a day (I'd say probably 2 or 3, but no more than that). Or maybe even limit it per week (so only 2 or 3 per week).
Even so, I don't know because there would be little incentive to actually purchase CE with real money, as you would be able to do 5 runs of Tier2 (with 400 mist energy; 100 from natural regen, then 300 from your 3 mist tanks), let's say, and end up with 35-40k, which at current prices (around 5k), would get you to be able to buy between 700-800 CE. So I don't think it would lower the costs of CE, but raise them instead, as crowns would be in even higher supply (and significantly less demand), while CE will still be needed for crafting above 3star.
But I would definitely like to see some sort of quests (repeatable or otherwise). Maybe their reward could be something like 50 CE? That might be a bit steep, though. A quest like "Defeat the Jelly King!" for a mist tank once a week, maybe.