Is it possible to clear the prisma story/missions with only natural AP???

It’s possible but it also means that you have to work thorough and quick tbh. I’m a little disappointed that they gave people such a short window of time to fully complete the event

Same, i 'm working on Mede a side mission. I have to beat up 30 skeleton which cost 60 ap. I tackling the Ocean D rank, I need a better place to make it more efficient.

I feel the same. Other than the materials I need for my Raikou’s 4th Ascension, I’m only interested in building up Chloe due to my lack of a strong ST Archer

I’ve gotten through The First Lady Raid and I have Chloe at level 40 but I’ve still got a long way to go

I think it is probably possible, but you would have to be really careful not to waste a single moment of AP regen (i.e. make sure that your AP is never completely full for an extended period of time).

According to the walkthrough on this site, you need around 2840 total AP, assuming that everything goes smoothly. You get 288 free AP per day (through regeneration), and I *think* that we get 11 days or so to do the event (you should double check on this, because I could be wrong). If that is the case, then you should have 328 AP to spare.

I could have made a mistake somewhere, so please double check for yourself and don't take my word for it. Also, this is under the assumption that everything goes completely smoothly. If you accidentally sleep in one day, or get busy with work or something, and let your AP bar stay full for too long, your 328 AP cushion will shrink. If you fail a quest or a raid, that will obviously set you back some AP. Also, I think that you need to ascend Chloe 3 times at one point, to finish one of the quests. If you need to obtain additional EXP cards in order to do that, then that will obviously cost extra AP as well.

Your current level also matters. If you are lower level, then you will have the drawback of having a smaller AP bar, so it will get full quicker, which will require you to be on your game more often to keep it from staying full. But you would also have the benefit of probably gaining some levels during the event, which would give you some free AP every time. If you are high level, then the reverse is true (easier to keep your AP bar from staying full, but you get no free AP through leveling).