SCARLET NEXUS

This method can get you ~100k exp in under 2 minutes

When I was started this I didn't read the comments of the other guide at first but after completing the boss one extra time, all the menus and cutscenes and scripted combat was really painful to go through, I figured there must be another way.

TN RyAn G originally posted this video:
Here is the text version with my own additions and findings:

- I recommend you play as the character you got everyone to bond level 6 as, as they will help you in battle more often
- Fully upgrade your weapons and equip them
- Equip System "Double Edged Sword", Combat Experience Assist, and Special Bonus Contract (DLC) if you have it

Method 1 (With Brain Field)
* In the exchange menu of the shop, exchange for up to 10 Brain Field Gear
(It requires 1 Battle Record S, 1 Other Ecology S, and 2 Other Ecology C's. By the end of my playthroughs I had at least 60 of each item.)
* Hit Up on the D-Pad to fast travel to Sumeragi Tomb > 7. Memories of Impasse
* Upon walking into the first arena, bait the first two Session Pound's to explode. After they do, use your Brain Gear then activate Brain Field. This is done early enough so you have a 1.80 multiplier when fighting the Chinery's, but also late enough to give you as much time as possible fighting them (you'll likely be relying on your teammates to extend your Brain Field time)
* When the two Chinery's spawn, initially try to hit both of them with your attacks because you're aiming to kill both of them during the Brain Field. Your EXP bonus will go away if you run out of time missing you at least 6k-8k EXP
* When the fight is over, teleport to the hideout (really any non-Sumeragi Tomb location). This will respawn the enemies
* Teleport back to rinse and repeat

Method 2 (Without Brain Field)
* If you don't have the materials for Brain Field you can still do this for 65k exp per run for nearly the same amount of time
* My approach was to have Arashi, Hanabi, Kyoka, and Tsugumi tied to one SAS menu and the rest on the other
* After baiting all the Session Pound's to explode and spawning the Chinery's, activate the 4 SAS with Arashi and the others and burst down the first one
* After killing the one, turn to the second and use the Combo Vision with your other 4 SAS partners (Gemma, Shiden, etc). This should knock over the second and allow you to burst the rest of it down for a quick fight
* When the fight is over, teleport to the hideout (really any non-Sumeragi Tomb location). This will respawn the enemies
* Teleport back to rinse and repeat

With this approach it took me 2 minutes and 20 seconds at level 64 for a complete loop, and an entire minute of that was fast traveling. Since I was on the One X I imagine it would be even faster with those playing on a Series X|S.

This netted me just under 99k experience (I don't have the Special Bonus Contract so those with it should be able to eke out around ~105k around 117k (EDIT: Thanks to SquiSquiSquidio for the numbers

If you hadn't already invested in invulnerability for Brain Field (2x Brain Field: Reduce Damage) I'd recommend that so you have no trouble whatsoever during the fight..

I got to level 75 using method 1 before I had to switch to method 2 since I ran out of Other Ecology C's

I have also individually confirmed that difficulty does NOT get you more experience so might as well play on easy, you can switch the difficulty at any time

Happy hunting!

You need to be at least level 80 to purchase everything in the Brain Map. This guide uses Brain Field (Arashi or Luka's powers work also, just not as well for me). You need Brain Field Gear for this. You can exchange easy to find resources for it at the shop in the hideout. Thanks D4rkTrooper90 for the reminder.
While the other guides are great, I recommend using the Special Training: Jewel Pool Cleanup mission, which you unlock after beating the game.

With this mission, you only fight the extremely fast Jewel Pool (a lot of them). You have 20 seconds to kill one before it runs off. However, if you do kill one, you get a LOT of experience points. Furthermore, I can personally confirm experience plug-ins work.

Here are the Plug-ins I'm using:

1. New Combat EXP Assist*
2. Improved Combat EXP Assist*
3. Combat Experience Assist

Brain Field: Time extension 1 & 2 also work wonders, as does increasing your Platoon's bond levels, so they'll extend your time also.

You should also have the following settings turned on:

1. Auto Lock-on
2. Aim Assist
3. Aim Assist (Locked-On)

I'm on my second playthrough in Kasane Standby Phase 5, starting at level 71 and gained 9 levels in 2 runs, killing 6 my first run and 9 on my second, using unlimited Psychokinesis on them while inside Brain Field.

It's unlikely you'll reach level 80 (the level needed to learn all skills) just by playing through the entire game even through NG+ though I stand to be corrected. I just farmed XP by replaying the last boss fight over and over, as one full run will give you about 100k-150k xp and should only take about 10-15m. You can use the EXP bonuses during brain drive/field for some extra xp.

This method is one that works after the addition of challenges. It will take longer than Kt Echo's method, however some bits of this one are easy enough to speed that one up a bit.

First complete the Musubi questline. If you complete all of the Musubi code inserts, you get an Improved Combat EXP Assist module. The module gives you 8% more experience in a fight and does stack with the Combat Experience Assist(5%) and Special Bonus Contract* (5% and is DLC) for 18%. All the Musubi codes are here: https://scarletnexus.fandom.com/wiki/Hidden_Codes
They are case sensitive and I recommend using the Xbox app to type them in easier.

I do not know if any of the exp boosters increase challenge award experience, but I used them anyway because it was worth it to try.

The easiest challenge to complete is to collect 1 Million Money which will give you 1 million EXP. I got this by selling 60 or so Other Ecology S's, all the attachment's I made for the 100 attachment's achievement, and the 2 challenges involving Guardian Vision's and Assault Visions. I did end the game at 1.4 million to so it wasn't really needed to do that.

The second easiest challenge is for your party members to activate brain drive 400 times; it is worth 500k experience. I completed playthrough 2 at like 392/400, it is worth it to get this by clearing our floors in Sumeragi Tomb.

There is another one where the playable character activates brain drive 300 times, but after all this I am only at 189/300, so you likely won't get this unless you specifically grind for it.

Completing quests up to 30 where you get that achievement do not give you much experience. The 7 challenges up to 29 give you 211,900 experience which isn't that much. The next 8 challenges from 34 to 68 quests completed give you 3,360,000 experience if they don't give a boost from the above items. 3,964,800 if they do work.

Tips for completing the quests.
* I recommend doing them on easy and solo. Most enemies target you anyway even when you have party members so it won't be much of a change with the exception that you have to clear your own status effects now and get no free heals. You also don't want your party members killing the thing the wrong way or hitting it when they shouldn't and the quest not counting the kill.
* All Combo Vision quests seem to not like you ending it with a Brain Crush so make sure to equip Attack Damage Specialization to lower brain crush chances.
* The "While SAS blank is active" quests only need it to be active when the monster dies. So you can get it to Brain Crush state, turn that SAS on, Brain Crush and get the quest.
* All other quests are fine to use brain crush to kill the enemy on as long as the enemies health hits 0 with the attack that breaks it's crush gauge.
* Intercepts and perfect Dodges are much easier with Clairvoyance active.
* To get Psychokinesis finishes on Pound's, I recommend level 6 Duplication for Cushion's and Perfect Dodge Intercepts for Missin. Missin's always go down with Intercept's and Cushion's always go down with shell breaks.
* Important Mission - Yuito quest - Brain Field Super Armor - This is apparently just a bad translation. You just need to Brain Crush 2 Buddy Rummy's at the same time. I got this by the elevator downwards in Mizuhagawa. Source I got this from is here: https://steamcommunity.com/app/775500/discussions/0/30562379...

If you want to do only 64 quests and then Kt Echo's method. These 4 are the most annoying quests.

* Going To Togetsu x 2 quest - My method for Kasane is fast travel to Mountainside on Hieno Mountain walked down the mountain to the locked in fight area and then back up the mountain toward the next one. Fought the Rainy Rummy's and entered that area just a hair below activating Brain Drive. To kill them I recommend Hypervelocity, Duplication and optionally Psychokinesis.
* Want To Learn More - Kasane quest - Getting the Follow Up Attacks on the Winery Chinery's is very annoying. Kept killing them with my sword. I recommend using Electrokinesis to stun them as Chineries are jerks and I got the second one the first try with this .
* Veteran Experience - Yuito quest - Psychokinesis read attacks are where you perfect dodge a melee attack when Clairvoyance is active and hit RT. This one isn't hard, it's just a lot of waiting for SAS to recharge.

If you wan to do this before the end of the story like me, just to be extra sure you are ticking things off as you go and arent missing anything before you start a second playthrough etc, then do this

You will be looking to knock out this achievement near the end of the game, so play the game naturally until standby phase 11. With all team member on bond 6.

Then go to the hideout and press x on the tv. This will let you play missions, including previous bosses. The missions only last about 5 minutes and net a lot of exp. Eg I beat coil moil and got 250000 for 5 minutes of battle time.

Ive practiced defeating coil moil and im getting it done between 3 and 4 minutes at 200000-250000 a time. Use the exchange in the shop to buy brain gears.

Method - Duplication + Pyrokenesis keeping hitting with x until x promt appears (Hanabi's bond 6 skill) and smash it x for major damage, rinse and repeat.
Before coil moil dives back it the ice trigger a brian drive using brain gear and do as much damage as you can.
After brain gear time runs out go back to duplication and pyro. If theres a little health left, finish with combos and electrokinesis