I managed it today finally, Rngesus took pity on me I guess. The team I used wasn't exactly f2p, but still not Ronin level of p2w.

It depends on how many difficulty reduction is in place. If only 0-1 like what I was facing, I'd wait until you're at at least 410k BP with your carry individual BP at around 145-150k. That's what I did and it still took me the entire day to get from 370 to 380.

It's not f2p friendly, quite p2w actually, just not Ronin level p2w, but I used Edo Deidara, Kakuzu EGF, 5KM, earth main.

The gist of both 370 and 380 is you need a ninja who can do 2 things: 1. Stack up a lot of dmg during wave 1; and 2. Deals dmg to as many targets as possible with his/her mystery, so as soon as wave 2 hits, you can oneshot as many enemies as possible. Edo Deidara (with at least scaling passive sb) fits the bill.

There are similar ninjas to Edo Deidara that are more f2p friendly, but it's also harder for them to survive. You could look up a Youtube channel by the name of "Sirld kiri" for other ideas, I did look at some of those videos for reference while doing my NE. Though China had many more sb ninjas b4 they had exam 341-380, so not all of the options shown there is available to us yet.

I did all mine at 410k BP with a the most stacked ninja being only 140-150k personal BP, with no Ronin, though. :P

My Edo Deid and Kakuzu are nearly full sb, but they are not fully sb. Both of whom only had 4/5 skill broken. So yes, it's hard, but no, it's not as hard as you're saying.

Well, you'll need one of your ninja at around 150k BP to get through the level, so if you spread and not stack, you might have to wait until around 550k-600k to be able to do 370-380.

The reason why Kakuzu is used in later exams:
1. he heals 2 Akatsuki in the team every rounds and give them double standards (passive breakthrough)

2. he can either use his mystery every round if team chakras is 50+ (Y+2 mystery sb) OR he can stack up a crap ton of dmg whenever his mystery kills its target (+2 sb)

3. his dmg scales with total chakras your team has (passive sb).

To get Kakuzu and get him to 4*, you need 180 of his fragments, each cost around 180+ cps each. And then it depends on how lucky you are with skill trials, but if you want to be sure, you might need another 100 of his frags to get any important sb you couldn't get with trials. So it's a long and hard way ahead of you.

As for Edo Deidara, scaling passive is a must, spiders and mystery are recommended, chase and standard can be lived without.

nope, only 1 reduction. I'm the second person in my server to pass them all. I can give ss proof if you wish. Also, he's talking to someone at 200k BP, by the time said person reach 400k BP, his/her server will have reduced the difficulty to more than the amount I had to deal with.

yep, needed to stack up Edo Deidara to heaven anyway. It was a high risk, high reward lineup since I usually need 9-10 rounds to kill all puppets. But when that happened, Edo Deid was stacked enough he oneshot like 2/3 of wave 2.