Not really a guide but you'll get the point in any case I hope.
The Angel's Chest quest is a repeatable quest. In other words, it may be done as many times as desired. You start at the Ancient Tree Greendeita
; receiving the quest from an angel underneath the tree. You will be asked to collect 10 Greendieta Souls
You then will have to enter Greendieta Caverns (i.e. "Sky City") The routes and entrances to which are featured on the sticky. The angels
in Greendieta drop the souls. The Boxes and the Elementals do not
. Unfortunately; boxes these days are going for abou 50 mill...I farmed the area on Monday and didn't get much profit. However (a plus!) The Boxes on the 2nd
level of the Caverns occasionally contain lvl6 Toxin, Slowmo, Panic...etc debuff lapis. Which doesn't go for much but is still money in the longrun
a boss in there but I've never, ever seen him and he is seriously hard to beat.
Return the quest to the same place and do it all over again if you like.
(Note that even if you collect 50 souls only ten will be handed once you return the quest. Simply take the quest and wait until the icon above the angel's head turns blue again to return the rest...repeat and enjoy.)
The differing portals are a complete and total pain to find, it took me a couple of tries. Try and stick to the guide on the map and you should be able to find it.