If you want to see memoirs by dungeons: https://nierrein.guide/database/memoirs

Refer to the bottom of this guide for a glossary of terminology used.

BASIC MEMOIR GUIDE

PvE

Use the crit damage set (The wanted man) or the 30% ATK set (A chance for conflict - aka berserker). Aim for crit chance and crit dmg substats. Save any crit chance and crit damage primary memoirs of different sets with both crit chance and crit damage substats from any set.

PvP

CDR set is mandatory and cannot be broken, so farm a lot of this. Same substats apply here, crit chance and crit dmg substats. Agility is also useful. Run 1 primary agility, 1 primary crit chance, and 1 primary ATK.

GENERAL ADVICE

Level memoirs with promising substats to 9 to see if they're good. Stop if they aren't. It's okay to upgrade whatever correct primary you get at the start. Be picky afterwards though; 2 substats of crit chance and crit dmg. Auto-selling 3* memoirs gives a lot of gold, but they're pricy too.

In PvE, you'll want to be using a combination of memoirs such as:
a) 2x (small set) of the set of your choice (Crit damage set or Berserker set), consisting of one crit chance main and one ATK% main; and a third piece that is a crit chance main from any other set, so that you're able to reach higher crit chances, meaning more consistency. As you close in on 100% crit chance, you'll want to start pivoting to more crit damage instead.

b) 3x crit chance main from 3 different sets, usually on an unit that has no crit chance passives from either its own passives or weapons', allowing to reach 100% crit chance with relative ease.

c) A full set of your choice, 1 crit chance main and 2 ATK% main pieces; this is when you have enough crit chance passive that you can easily reach 100% with only one crit chance main piece.

In all of the 3 cases, you can switch any crit chance main with a crit damage main, should you have enough crit chance to allow the trade off.

Ideally, you want to aim for 100% crit chance and 200% crit damage without any crits passives.

HOW MEMOIRS WORK

The first row may have any primary of ATK, DEF or HP. They can be a % based multiplier, or they can be a flat addition. The other two rows may also receive these stats. The second row may also receive crit rate or crit dmg. The third row may also receive agility. Any stat may be rolled for the substat stats. Substats are improved every 3 levels, meaning substats can be raised up to 5 times. The bottom of the image indicates the maximum value a substat can start at, as well as the maximum value a substat can end at presuming it was raised each time. Substats are improved by a random amount upon each level, for example crit dmg can receive a 4% boost or it can receive a 6% boost.

First and foremost, it's not recommended to farm memoirs unless you can farm stage 10. There are plenty of ways to boost the power of your team otherwise, and all these things should be done before one considers beginning to farm for memoirs. Farming for memoirs takes a long time and many thousands of stamina to cobble together decent sets, so it's best not to waste your stamina in stages with suboptimal drop-rates; you should spend your time doing something you have to do to improve your power, like leveling and evolving your weapons and building an appropriate elemental deck to tackle a 10th stage. Improving memoirs becomes increasingly difficult the more optimized your current memoirs are, as statistically, the chances of rolling the correct piece with correct primary stat of the correct set with both the substats you want (crit dmg and crit chance), to then have them enhanced 5 times out of 5 without rolls being wasted on useless stats, are very, very low. It's a slow marathon, which is why you shouldn't waste any opportunity when the relatively rare half stamina 2.5x memoirs drop rate event comes around, usually for a week to 10 days. Also consider clearing the story as one of the later chapters gives a memoir drop rate boost perk.

Once you are able to comfortably auto farm stage 10 of the dungeons, you should set your auto sell feature to sell any 3* with any number of unlocked substats (1 to 5), so that you'll only receive 4* ones.

The fastest way to farm a dungeon is with a team of strong hitters (bold vigor ideally) with off-type guns that counter the dungeon f10 element, as guns have the fastest animation when used by a non-gunner character, as long as it 1 hits the monsters.

With guidelines established and the basics of memoirs out of the way, the rest of the guide will be in-depth analysis on sets dungeons drop, strategies and requirements for clearing the boss along with more in-depth building advice. There will be a summary of every section, as well as an FAQ at the end. Feel free to submit questions!

DUNGEONS

15% ATK SET
Critical hit damage up by 40%
HP up by 25%
Defense up by 15%

SUMMARY: This is the starter dungeon to farm to get some good PvE sets, to allow you to farm other things.

OVERVIEW OF SETS: This dungeon drops the best general purpose PvE set, the CRIT DMG set, The Wanted Man. The force requirement here is the lowest out of any dungeons, making it a good starting point to build some power and start tackling more desirable dungeons if you find yourself unable to clear them when beginning memoir farming. The HP set also drops here, which is usually used by tanks with provoke in both PvE and PvP, and also by healers, mostly in PvE.

CLEARING STRATEGY: This dungeon requires a wind deck. We want companions that boost wind damage and reduce water damage. The last slot can be any leveled companion for the utility of its skill. Gayle's EX weapon evolved can be a significant help here. Our only other free source of a wind EX weapon is Griff's gun. It would be usable if one had a character who could use guns. Other weapons will have to come from the gacha, whether it be evolved and ascended 3s or evolved 4s, preferably the latter.

For manual, with a wind deck we can clear this dungeon at the 75,000 force range. Use a few skills in the second wave to generate character gauge. When you meet the boss, wait until he uses his first skill. When he does, lead your combo with your companion that has elemental advantage, then use skills on your best damage dealer first to get their character skill up. Follow with your other two units to build combo, ending with your carry's character skill and the boss should go down in one sequence.

Auto requirements for this dungeon will generally be in the 95,000 force range, and you may need to farm manually at the start to get together some sets that can do it consistently. Consider seeing if you can keep auto off for the first two waves and then turning auto on for the final wave to automate some parts. This boss gains a massive damage buff and spams attacks under 25% HP, so ending the fight swiftly once it reaches that point is important.

Agility up by 20%
Attack up by 30%. Defense down by 30% for 60 seconds
Defense up by 30%. Attack down by 30% for 60 seconds
Critical rate up by 15%

SUMMARY: Farm this for the 30% ATK set for the highest damage output in PvE.

OVERVIEW OF SETS: This dungeon drops the other optimal PvE set, the 30% ATK berserker set, and that is the main reason anyone would farm here as the other sets are not very desirable. While it offers a relatively large amount of attack, it also comes with a drawback that usually makes it unsuitable for use in higher end challenging content, -30% self DEF debuff for 60s.

The crit rate set has the lowest output in the game relative to other sets that improve our damage. This set is worse than running no set at all and instead taking crit rate or crit dmg primaries. It's also worse than running a broken set with an additional crit primary. The DEF set is usually not worth pursuing as the HP set from Dynast dungeon will lead to higher effective health in pretty much every case. The AGI set is useless in PvE and there's little reason to use it over CDR set in PvP.

Compare with Dynast; while we get the best PvE set in the game here, we also get the worst one, whereas Dynast drops two middle-ground PvE sets. Once your Dynast sets are situated, one could consider farming here for PvE purposes.

CLEARING STRATEGY: This dungeon requires a dark deck. Officer is actually very difficult to auto. There are a few key conditions we have to meet to do it consistently. We need to be able to clear the first two waves very quickly to save as many skills as possible for the final wave. We need good damage output to be able to clear the additional mobs that spawn with the boss quickly. Finally, we need to be able to kill the boss before he uses his first AOE.

The first AOE has a chance to blind our party members, which wrecks consistency in auto if it lands. It takes very high damage output as well as reliable crit rate in order to clear this consistently on auto. We can use semi-auto strats here; keeping auto off until the final wave and targeting the boss manually can automate some of the process.

For manual, the boss is squishy. Just target the boss and have your skill rotations up and he should go down if you're running a proper dark deck. This can be done around the 85,000 force range. For reliable auto-clear, it's less about force and more about optimized memoirs, but 100,000 is a reasonable range.

Attack up by 15%
Critical hit damage up by 40%
Critical rate up by 15%
Agility up by 20%

SUMMARY: Clear this for the premium currency and don't farm it.

OVERVIEW OF SETS: Global has the advantage of having content rushed for us. This dungeon was good in JP as it was the primary place to farm the AGI set, which was the meta set in PvP before the advent of the CDR set, and it also provided you with two good PvE sets and one suboptimal one. However, since the next dungeon was rushed, there's little to no reason to farm here. There's better places for PvE sets and the PvP set is not particularly helpful.

CLEARING STRATEGY: For clearing, the boss has a mechanic of needing to deal enough damage to prevent a big nuke that happens around 15 seconds into the fight, so you may consider saving some skill rotations for that.

Increases chance normal atk will be 3-chain or more by 10%
Weapon skill cooldown reduced by 30% at start of battle
Damage taken reduced 15% 3 times at the start of a wave
Attack and defense up by 30% for 30 seconds when your HP falls below 50%. Once only

SUMMARY: Farm this for the 30% CDR set, which is optimal in PvP.

OVERVIEW OF SETS: The Chain set, the DR set and the 30% ATK and DEF for 60s once you go below 50% HP are all relatively terrible and hardly have any use. 

The CDR set is the biggest prize of this dungeon, as it's the optimal set to be using in PvP. Skill activation is another way of going first, and while normal attacks can miss kills occasionally, in PvP skills are almost certain death to most characters, especially after the regular attack phase.

CLEARING STRATEGY: This dungeon requires a fire deck. EX weapons that cover that are Akeha's and Lar's. Evolving them will significantly help with the consistency of your clear. This boss can check two things; first it checks your DPS, and if you fail to kill the boss it will spam big AOE damage at low health similar to the Dynast boss, which is a durability check. Leveled elemental companions are a huge boost here, the best being fire book and wind pod. A healer may be considered if your auto runs are inconsistent, 3* FX66 being the recommended one.

Around 100,000 force with well-optimized memoirs will be what most compositions are looking at as an auto requirement. For manual play, it can be cleared in the 90,000 force range by saving our skills, previous strategies of trying turning off auto until wave 3 still apply.

All allies' attack up by 10% for 60 seconds.
All allies' HP up by 10%.

OVERVIEW OF SETS: The two sets from this dungeons are not very desirable. 

The temporary team ATK set could be useful in subjugation if you don't manage to reach 10 stacks of ATK through the common means such as weapon skills, support character skills and companions.

The Team HP set is very marginally better by 5% if you need all 3 of your units to wear defensive, HP based memoirs to survive and tackle a difficult fate board or deep abyss tower floor the slow way, poison & heals. Otherwise the regular individual HP set from Dynast is better.

All allies' agility up by 10% for 60 seconds.
All allies' defense up by 10% for 60 seconds.

OVERVIEW OF SETS: Once again, these two sets are not very desirable either.

The team agility set could see some niche use in very specific teams, usually consisting of a tank, a healer and a dps to clean up, the tank could use this if they feel tanky enough to ignore a HP set for 25% extra HP. This way it helps the (usually) healer - builty very AGI oriented - to get the first auto attack in, allowing for a safe provoke activation.

The team DEF set is pretty much worthless. However, there are certain EX5 quests in events that require specific triggers to enable 20 or 30% damage increase toward the boss, usually based on the unit released along the event, which could be - rarely - something along the lines of “Deal 30% more damage when you have DEF buff status”.

All allies' attack up by 10%.
Chance of a 3/4/5-chain occurring up by 5% each for all allies.

OVERVIEW OF SETS: The chain set is absolutely worthless in every scenario.

The team permanent ATK set (affects loadout ATK stat as its not temporary) is a very, very useful set to have at least 6 sets of.

It's used mainly in Subjugation mode, but can also be used in regular “challenging” quests. It's equipped by the support(s) in the team that are usually not going to deal significant damage anyway, like healers or pure buffer supports.

In Subjugation, each wave ideally runs 2 supports running this set and 1 carry DPS that is buffed to make that damage counter skyrocket. It's by far the best option for your supports as it provides a meaningful passive damage boost to your units that actually deal enormous amounts of damage. Read more about subjugation in the article about it in the Guides section.

PvE
SUMMARY: Use ATK sets and crit dmg. Crit substats are ideal. Set can be broken for another crit primary as you build good sets.

ATK sets and crit dmg sets are what you will be using here. For primaries, we'll take one crit rate or crit dmg depending on what our substats provide us. At 28% crit rate, we want 1.8% crit dmg per 1% crit rate we add for optimal returns on damage, so try to maintain that of balance (of course, as you lean more toward 100% crit rate, crit damage becomes much more impactful). The other two will be ATK primaries - or breaking the set as mentioned before.

Something else to consider as we're beginning to build sets is that there are a lot of memoir sets we won't really be using, and given we need 3 strong memoirs in a single set, this can take a while to put together, since we need 3 sets too. If you end up with a good crit rate or crit dmg primary from a useless set, if it rolls well on substats it can be worth breaking up your set bonus if you have poor rolls. 2 set bonus would still be recommended. We get better returns out of crit primaries than we do ATK primaries, so you can just save crit primary rolls. Optimally speaking, we'll end up with a full set eventually, so consider this a temporary measure to boost your power as needed.

PvP
SUMMARY: Use the CDR set and do not break it. Crit substats are ideal. Agility primary is important.

CDR set is king, and unlike in PvE under no circumstances can it be broken. Primary building is also different here, though a bit more straight-forward. In PvP you will want 1 AGI primary, 1 Crit primary and 1 ATK primary as a general baseline. Crit chance is key for consistency, as with using a full CDR set rather than breaking it to facilitate a higher crit chance is not an option, you will want to focus on memoirs that rolled high crit chance substats more than anything else. According to your own standards, when you reach your threshold of desired crit chance, focus on increasing your crit damage stats - crit damage is a worthless stats if you dont crit consistently. A good crit rate / crit damage ratio would look like 70% / 200% and above, or 80% / 185%+, based on what you're satisfied with when it comes to crit chance. Naturally, having crit passives on the costume itself or the weapons equipped will increase these thresholds.

AGI is desirable as a substat but is a complete luxury, don't trash a piece because it has only crit chance and crit damage substat and not AGI, because crit chance and crit damage are more valuable, having a base AGI roll on a memory can help with your units going first, allowing you to snipe an enemy unit.

There are cases where you want to equip one of your units with 3x AGI main with high agi substats (along with 3x subjugation weapons ideally, as each gives a 30% temp AGI), completely disregarding the other substats. This happens mainly in tank teams, where you want your AGI “junkie” to attack first so that it allows you to safely use provoke on your tank before the enemy has a chance to snipe one of your units.

FAQ

Q: Should I sell flat stats?

A: Flat ATK is solid for a few reasons. The primary one is it's really damn hard to get memoirs with amazing substats, so getting more chances to get those highly desirable crit rolls can boost your power a lot faster. Past that, it has to do with characters that have ATK in the 3-4.5k range not losing too much out of the flat ATK set, though anyone with over 3000 ATK will strictly get less ATK from the 600 cap of the flat ATK primary vs. 20% ATK from a % based primary. Flat HP/DEF can provide a larger amount of HP/DEF on many units, though generally we don't build for bulk.

Q: Is, say, ATK set bonus any different from ATK% as a primary stat on a memoir?

A: Set bonuses apply differently in the formula than primary stats. A primary stat of 20% ATK on a memoir is only applied to the character's base ATK; for instance, a character with a base ATK of 1000 would get 200 ATK. A set bonus of 15% ATK would be added to any Vigor (or ATK%) passives the character or weapon has. This part of the formula multiplies with your character's ATK after weapons and companion are considered, which is a significantly higher number!

Q: Should I break my sets?

A: Yes, you will break your sets a lot of times, to guarantee a higher (ideally 100%) crit chance. Breaking the set will allow to reach higher crit chance with much more ease without losing much value from the set.

While it's not exact as the character page doesn't reflect your ATK stat properly, ATK * crit chance * crit dmg can give you a general idea of your average damage output.

Q: When should I be satisfied with my memoirs?

A: 15-20% crit chance or dmg combined on subslot is a solid memoir. Past that is a lot of stamina to optimize a bit more. Consider if you have anything better that you should be doing, like evolving weapons, leveling companions and if you have the stomach for it, cube farming. Bear in mind we only need 27 memoirs for Subjugation in the future, and you will reach that point quickly.

Q: Is Agility worth it in PvE?

A: The only thing that agility influences is turn order, which isn't very significant given this is a game built around building combos with your character's skills. Agility has no influence on skills interrupting turn order, so no, agility isn't useful in PvE. This is purely a PvP stat.

The only place where it matters is if you're pushing high subjugation scores and want to maximize your consistency. As the Moose in subjugation mode has 1100 base agi, you may want to consider giving your units one agi primary memoir (your supports, not your DPS) not to have the moose do double auto attacks before all your 3 units have done theirs.

CREDITS

Yuuru - Without his YouTube and many, many hours of work reverse-engineering all the formulae in NieR, there are so many things we wouldn't know. The crit dmg:crit rate ratio is lifted from Yuuru's work. The memoir chart at the top of the page is his work. If I'm discussing the formula anywhere within this guide, it's all thanks to the information Yuuru painstakingly discovered through testing. We would know almost nothing about this game if not for him. Follow his content for the most in-depth analysis on NieR: Reincarnation you'll find!

Aerius - For assisting me with some formatting, streamlining and being my editor.

Keziah - He did all the formatting for this guide on this website!

TERMINOLOGY

1. Primary = The top stat on a memoir.
2. Substat = The four stats below the primary on a memoir.
3. ATK = Attack
4. DEF = Defense
5. Chain = Your chance of dealing additional hits in your character's normal attack.
6. CDR = Cooldown Reduction
7. DR = Damage Reduction
8. CRIT = Critical hits
9. DMG = Damage
10. EX weapon = Dark memory weapon
11. Cube = resource with which to evolve EX weapons