I've just made it to 8-2 and so the option for 5 star gear is open to me. However, at the current energy exchange rate, Eternal Orbs of Alchemy are a little
Prohibitive
cost-wise
to my ability to actually make anything in a timely manner.
I've heard late game, Eternal Orbs are actually pretty easy to get, but is that just at Firestorm Citadel grind, which requires already having 5 star gear to get to, or is there another place I can go to farm them in a relatively timely manner?
That's insane. I just would not have played the game if I needed that many crowns to progress.
Back on my "alchemy orbs should not be primarily obtained with energy and/or be removed from the game entirely" soapbox.
But good to know any T3 will work.
Before we had alchemy orbs, you just always had to pay the full energy cost for every craft. You wanted a 5 star item? Cough up 800 energy. No other option.
Sure, you basically had 100 free energy every day, capped at 100 stored, making it a possible 700 energy to craft that 5* item you wanted, assuming you didn't want to play that day. Because you also needed to use those to actually play the game, at a rate of 10 energy per floor you visit. Adding in orbs that you can farm up, and which you're also handed for free in select rank missions, made it a lot less grindy to acquire new equipment. The same update that removed elevator costs also removed mist energy and added in orbs of alchemy.
Just because the system is better than it was doesn't mean it's good enough.
Frankly, I should not have to spend more than an hour, on average (not accounting for variance in RNG), on a full set of alchemy orbs, ever. At the current crown and energy rates, eternal orbs take over 5 hours. Sure there's a chance some will drop but I'm my experience it's a VERY low chance at least prior to T3. Lucky to get one in that 5 hours type of low.
Yes, any deep levels will work. You don't need to focus on Firestorm Citadel.
By the way, the guild Lancer Knightz used to run a data collection project. You might be interested in their page that analyzes Orb drop rates from missions:
https://wiki.spiralknights.com/Lancer_Knightz_(Guild)/Mission_Rarities
Just play any tier 3. Arcade is fine. You can also just get invited to vana runs, but eh. And it's not that eternal orbs get easier to acquire later on, it's just that you spend enough time in tier 3 and don't constantly decide to craft new items so eventually the orbs just pile up if you continue playing. There's also danger missions, but you'll definitely need a carry for those. As a side note, the apocrea event is also quite decent for boxes, but it's also not easy, and you might struggle finding parties since you're not already a Champion/Vanguard.
That said, energy is extremely cheap by historical standards. Count yourself lucky that orbs are this cheap. You could've been paying 10 000cr for 100e if you decided to play a few years ago.