Re: (Nutaku) Milenium War Aigis (English Version)
got 2 plat fairies and 2 gold fairies with todays fairy run (and 1 spirit queen).
which unit should i give the tin can to first?
or better yet, what to level so i can beat castle retake. that damn black armor and lich are preventing me to get to dragon hunting.
Just as a friendly advice I would save the tin cans for the last exp boost in order to save money. So gold Units is ~lvl40->50 and plat units ~41->50 (you should check the exp table in the wiki for the exact values).
Also I wouldn't further level up the 2 Julians, they might help you now but it's going to be wasted exp. If you have no other reliable soldier get 1 CC and then cannibalize the other with 3 gold fairies for a massive exp boost (again wait for lvl 40+ to minimize costs).
Regarding what to level might be tricky and will depend on how much time/events you might be willing to skip or just go for bare minimum.
-A CC gold Soldier will be really useful, often required to get things done easier.
-A CC healer is another requirement for later stages so don't forget to give some love to Iris
-You also seem a bit lacking on mage/witch department, so as a minor objective getting cloris and the white beard guy would be good after taking care of the previous 2 units
(Note: only go for male mage if you're not going to be using premium gatcha much, I heard the gold girls are quite good but I personally don't have any. Also the silver girl is also not bad with her skill being atk+ which makes her one of the highest atk mages if I'm not mistaken)
-Regarding archers you got both goddesses. They'll take a bit to CC but they're worth it. (Their downsize is their higher cost so you should try to get a silver archer CCed in the future, at cost 9-10 they're pretty solid units)
Regarding what you should do, it is a bit tricky situation.
I would probably get that soldier CC 1st (already at lvl34 so not much left), then quickly bring him to lvl20 and stop there.
I wouldn't work on many more CCs at this point, unit exp is low and getting any unit to lvl40-41 to use tin can would take a while.
My thoughts would be to get every unit on main team at least lvl30 and try to 1* castle retake and move on (abuse your soldiers skill and then use trashes as lighting rod). If you're still struggling to be done with it, try to get nanally or bashira to higher levels and abuse their skill to quickly take down the lich.
As a last advice, don't look down on silver units.
They're cheap, "easy" to CR and you can complete most of the content with full silver teams. Just focusing on the golds/plats/blacks will hurt you by limiting you to those units, gimping your variety of tactics you may be able to employ.
Yet, this is just my personal opinion based on how I usually play the game, it isn't in any way the best/most optimized way to play. And if you're willing to use SCs then things may take a different route.