Collection of tips from various sources here.
General Tips
- Exp growth is greatly reduced. Always try to have Byleth adjacent to the unit getting exp, particularly for the killing blow.
- Give a bow to every physical fighter. Some guides recommend giving a bow to every person, period, but I think I can trade them around if my mages really need them.
- Healing exp is not nerfed, unlike other exp. Get as many people as possible Faith D for heal. Mercedes, Ashe, Sylvain and Ingrid all get Physic, so C rank for some of them might be a good idea.
- Every physical fighter will master Brigand, and then Archer if they have the time. Every mage will master Fiendish Blow. No other beginner class is worth the seals or time for most characters, with a couple of exceptions.
- Going on that vein, every character should get to at least D+ in axes and then save scum until they pass their certification for brigand, as well as D+ for bows if I have the time and money.
On Grinding
It is definitely possible to grind in Maddening--just very difficult. It is also limited. I'm not sure if other routes have this, but in maddening each map is capped at 99 turns.
In essence, grinding in FE3H boils down to having the bad guys whack your highest defense person until all their weapons break on his face. In the meantime, if he needs training he can reciprocate by hitting back with a broken weapon, therefore guaranteeing that you will get weapon and class exp for as long as possible. Problem is, given the 99 turn limit, causing the bad guys to break their weapons eats up about 40-60 turns already. With a unit with sufficiently high defense, however, this can be an incredibly fast way for one, or more, units to train.
WIth that in mind, it's good to have at least one of every broken weapon type in your convoy, so you can take them out at your leisure. To get these quickly, use lots of combat arts. You probably have to anyway given the extremely low damage output of units in the beginning with standard attacks.
I will save scum so that Byleth and/or Dedue get a defense level every level. Then I will give them a silver shield, Duscur heavy soldiers, and have the other be an adjutant to maximize their defense. This is crucial for recruiting other units, as it'll allow my Byleth to quickly train all the physical weapons, authority, as well as riding/flying/heavy armor if they're in the appropriate classes. Other units will try to train as much as possible on enemies that have broken their weapons, so that we can save time on lectures.
The things that Byleth CAN'T grind are Reason and Faith, as well as initially Heavy Armor, Flying, and Riding. With that in mind, it is VERY useful to do the choir activity every time until you hit at least D in faith, and when you are doing faculty training, to train armor, flying, and riding. Once you hit E+ for heavy armor/flying/riding you can save scum while taking certifications and then grind the levels. Just remember to use magic and faith as much as you can every chapter.
The units I want to recruit for Blue Lions include Hilda, Leonie, Petra, and/or Lysithea (what can I say...women in this game are just better imo). Ideally, I want to just train the stats needed to recruit them because I am very afraid of getting screwed with the random recruitment system...but I may not get the luxury for that. For future reference though, they require C in axe, C in lance, C in riding, and C or B in Faith respectively. All these are relatively easy except riding which I'll need to go out of my way for. I want to recruit everyone eventually for their paralogues and also because I don't enjoy killing students.
Lectures and Goals
As much motivation as possible will be spent on skills units are proficient with. I will try to save group tasks for people who do not have proficiency in riding/flying. The non-proficient skills will be assigned as goals because the experience here is not reduced by poor proficiencies.
With maybe one or two exceptions, everyone will get Faith D for the free uses of heal through both proficiency and manual lecturing. The next thing to focus on will be Axe and Authority, until they get at least Axe D+, then switch to Bow and Authority till they get at least Bow D+, for Brigand and Archer. Then they move on to skills their main classes will need.
For Felix, authority training isn't as urgent as he is better without a battalion in the early game. He will focus on sword instead.
For Dedue, heavy armor will be an early focus, with the hopes of reclassing him to armor knight ASAP. The hope is that, in conjunction with the heaviest shield I can find, Duscur battalion, and another defensive adjutant, Dedue will be so tanky that he can have enemies break their weapons on his face, allowing the rest of my characters to safely farm.
Reclass everyone except the people not using faith into monk to continue capitalizing on the free exp heal gives.
Chapter Rundown
Prologue:
Trade Claude and Edelgard's weapons and vulneraries to Dimitri and/or Byleth. Dimitri and Byleth take all the hits and do all the damage for max exp. Use forests to your advantage.
Try to head north with Claude and Edelgard to draw the enemy soldiers north, hopefully causing Jeralt to steal fewer kills near the end. Jeralt can't kill the boss so if he can only target the boss it's fine.
Chapter 1:
I bring Sylvain, Annette, Mercedes, Dimitri and Byleth. Felix does a lot of damage and I want to try to grind. Given that I had shared a meal with Annette and Mercedes maybe I should have left them home.
The A.I was really fascinating on this one. Advancing north causes all units to jump on you, which is messy at best and impossible at worst. Going west and killing Hilda, Claude and Hanneman causes the black eagles to all aggro and attack you in a way that's awkward to defend against as Hubert is within supporting distance of Ferdinand.
The best way to approach the mission is to go west, kill Claude and Hilda, then go back east to the starting position. Inch your way to the single square that only aggros Ferdinand, kill him with focus fire, then aggro Hanneman and kill him. With just Edelgard and Manuela left, cleanup should be relatively easy.
I trapped Manuela and farmed. Everyone got ok to good levels, except Sylvain who got a whopping +9 level. Trained most to level 4ish, and trained Dimitri's lance to C. Should have given his broken lance to Byleth. She did get some uses, reaching E+.
Aux Battle:
The game forces you to do an aux battle after Chapter 2. The enemy stats are more in line with hard mode than maddening, making it rather easy. Park all the units in trees and heal as necessary.
I gave Dedue the broken lance and got four enemies to attack him until they broke their weapons. Meanwhile the others kill everyone else. I then give Byleth the broken lance and grind.
Almost all characters ended up mastering commoner/noble, which is great. Dedue and Byleth were able to go straight to rank C on both authority and lance, which is amazing. Funnily enough, not a single person got a level up.
I will try to get one broken weapon of each type so she can hit C rank on everything. Given the 99 turn limit, she will be able to hit rank C for two weapons per auxiliary battle if she ever gets her Def high enough.
Following the lectures, the saint's day, and the seminar (which nicely bumps all my half motivations to full motivation), Annette can now use heal. Ashe and Sylvain JUST didn't make it. Arghhhh....I guess we'll have to go into the next match with just ten uses.
Chapter 2:
The enemies approach 3 at a time until they're mostly dead. Keep all the units near the starting position in a concave formation, sending Dedue out to lure if they stop coming at you.
I was tempted to trap the enemy priest in a forest and grind on him, but thickets on this map for some reason have their defensive bonuses halved, and I figure it wasn't worth the trouble given that he had 12 nosferatu uses. However...Ingrid would have taken double hits and 1 damage per hit, allowing me to deplete him in 6 turns. Had I managed to separate him from the other bandits a grinding opportunity may have been possible. Oh well. I'm getting tired of spending 99 turns per battle anyway.
Thanks to his Authority C, Dedue has Battalion Wrath, which would have been amazing if he had hit something on enemy phase, but alas he did not.
I manage to get all characters except Dedue Faith D. I figure Dedue won't need it since he'll be getting crazy bonuses from mastering al lthe skills anyway. I reclass Byleth and Dimitri to Monk, and switch almost everyone's goals to axe/bow, forgetting that I should have done axe/authority. Not a big deal, hopefully. Now that both Mercedes and Annette can use reason and faith magic, I change their goals to reason/authority on the assumption that they will use all their uses of heal every chapter and therefore get fast faith exp anyway.
Chapter 3:
With a whopping 8 units that know heal, as well as my brand new Leonie, I should have both enough firepower and enough healing to power through this mission. A couple of wrinkles however...it's a fog map, so I'll need to be super cautious moving forward. Dedue, Dimitri and Byleth will always be the front-most units.
The second problem is that there are NPCs I need to protect for rewards. I will heal them like crazy. Good thing I got everyone heal. The combination of the first and second problems turns the map into a unique challenge. Were it not for Catherine and her two guys, I would advance slowly and steadily through the map, always keeping my strongest units in the front. But the fact that they are charging forward means that I have to charge right alongside them.
The weaker characters (Ingrid and Ashe at this point) will be relegated to mostly healing, while the strong characters will tank.
The third problem is that I can't infinite grind because Catherine will eventually kill Lonato or die, though again the healing exp is a nice consolation prize.
I purchased kingdom soldiers and the stride battalion for a couple of units. By chapter 10 or so on hard you have more battalions than you know what to do with so I want to keep battalion purchase to a minimum. Plus, enemies do so much damage that a couple of hits would wipe out a battalion anyway so I like having a couple of units with no battalions to soak the hits.
The battle was very gnarly. I used torches everywhere for a test run and memorized enemy positions before restarting and using stride, hoping to kill a bunch of enemies off the bat. However, my plans fell through because this is Maddening: all enemy units have high avoid by default as is, let alone when they're standing in woods and thickets, so consistently hitting them is impossible. I had to turtle and even then I had many restarts due to being jumped by enemies in the fog. I lost one of the NPC soldiers but I had to continue because the turn he died on was so pivotal.
All of my guys were going on a healing frenzy, so they were all able to level to 4-6. In classic Ingrid and Ashe fashion, neither of them got a single strength level. Ingrid at this point can only damage people using steel lances and/or combat arts, while Ashe has been reduced to doing one or two damage per turn. If they do not get strength levels soon I'll be forced to ditch them and recruit other units. Dedue also has not gotten a single strength, defense or HP level which is amazing and upsetting to me. However, Dimitri, Sylvain and Felix are turning out very well.
Chapter 4:
Explored every time. Asked Lysithea for assistance. She's an adjutant on MU for the next mission.
I've discovered that training manually with proficiencies is better but that the exp you get for free at the end of each week following a lecture is not influenced by proficiencies. Therefore it is best to manually train people in things they're proficient with and set goals for things they're not proficient in.
I have managed to get most units to D+ in axe and bow, to barely make the threshold for Brigand and Archer. Authority is the next goal alongside whatever bases they will need for the future, so that everyone can use battalions.
Had Dedue gotten just two strength levels, he would have potentially been able to one shot the death knight with battalion wrath, a steel axe, and a bit of luck. Unfortunately for me his strength level is still base, and he's level 4 so he can't use reclassing to bump up his stats. So I'll have to avoid the entire center of the map.
I start from the bottom and move clockwise around the entire map, but FIRST I save scum literally a dozen times until Ingrid finally got her first strength level. I just couldn't take her crappy stats any more.
Clearing out the enemy in this fashion was actually relatively easy: I have so many healers that everyone was fully patched up following a round and I could advance on the next couple of units. The only hiccup was when an enemy used a battalion to shove one of my characters into the death knight's range, which resulted in an instant death and divine pulse.
The three mage reinforcements show up as I am reaching about the nine o'clock position. I meet them in the top center of the map, where I use one stride battalion to make all my units attack and use their own battalions. Thank god I brought battalions that have a wide hit radius, and I was also lucky that none of said battalions missed. To my surprise, I was able to go as far as the chest to the right, kill every enemy aside from the daeth knight, AND neatly finish off the boss right as the round limit was coming up. Leveling up was about average. My only regret was that Byleth didn't get to heal much. I'd very much like her to hit C rank Faith soon.
Overall, a surprisingly easy level. Every time I run this level on any difficulty should be like this.
Chapter 5:
Explored the first time, and got two requests for battles which would give merchants and renown...I think I'll take it because getting the merchants as early as possible grants more gifts and bait later.
Ate meals all times except the tea time with Rhea. Not sure if the tea was worth it.