Micromanagement (or micro) is the control of your units. For example, avoiding pikes while trampling an enemy army with cav, surrounding a lone battalion or clumping to kill a hero or building faster. Also includes where you position your army, the formation that you adopt, etc.
Stances in BFME 2 give different bonuses (see stances in game mechanics to see the exact percentages for each unit type). As a general rule, aggressive stance increases damage at the cost of armour, battle stance is the default one (so no bonus) and defensive stance increases armour at the cost of damage. That means that you should put units in aggressive stance when are attacking but not receiving damage (like when harassing a building), or when you want to deal more damage in a determined moment (when focusing a hero, for example). Use defensive stance when you want a unit to survive longer, or are being attacked but not dealing damage (when retreating, for example). For normal battles, use battle stance, since it is the most balanced.
Using stances can also be very rewarding in flanking moves: use battle or even defensive for the units that are sustaining more damage, while using aggressive for the units that flank (so they deal even more damage). Or use battle/defensive for infantry (the ones tanking damage) while using aggressive on archers to maximize the damage output.
The formation your army adopts directly influences the result of the battle. As a general rule, you deal more damage using a concave formation (so, partially surrounding your enemy), as more of your units are attacking at the same time. Concave formations are also more vulnerable to flanking. As a consequence, convex formations are to be avoided in most cases, as in an otherwise balanced battle, the concave formation will win.
Other consideration of formations is the positioning of different units according to their roles, strengths and weaknesses. For example, archers should stay away from melee infantry, and pikes should be spread through your army to cover possible cavalry attacks. As pikes are more vulnerable to melee engagements, also try to fight primarily with your swords, to ensure that pikes survive. Nothing is worse than fighting and winning (or losing) a important battle, and watching how your the remaining units of your army (not to speak of heroes) are finished by enemy cavalry because your pikes died in the previous fight.
Clumping vs spreading
BFME mechanics allow units to clump (this is, unlike in real life, you can have multiple units occupy the same space). Clumped formations have some benefits and disadvantages. In general, clumping is good to deal high amounts of damage to an enemy single target, like a building or hero, since more of your units will attack at the same time. The following video explains how to clump and shows the many uses that it has. Edain clump mechanics are the same.
The disadvantages of clumping are mainly, more vulnerability to AOE damage (such as Gandalf's wizard blast, Aragorn Blade Master or Arrow Volley), and a worse formation in standard melee fights, since as we saw previously, concave and surround formations are more effective.
Cavalry is one of the units with most micro potential. Well microed cavalry can deal a lot of damage to enemy units, thanks to the trample damage. To micro cav effectively, you need to understand how the trample mechanics work: to put it simply, each cavalry unit has a deceleration stat that determines how many enemy units can be trampled (that is, deal trample damage and throw to the ground). Once the cavalry has done that, they slow down (and trample no more) until they are no longer in contact with enemy units. As slowed cavalry is slower than basic units (swords and pikes), they can be chased and receive flanking damage until they exit the enemy clump. As cav deals trample damage, it also receives revenge damage. This is suffered just by trampling. Pikemen deal lots of revenge damage, and that's why cav dies almost instantly when trampling pikes. But other units like swords deal lesser amounts of revenge damage. You can see easily by trampling swords with beorns or trolls.
So we can conclude that cavalry is less effective against big clumped armies (unless in big numbers) because they will get stuck and possibly be killed. An exception is elite-heroic cavalry, which slows down much less (but is very vulnerable to pikes). As an example, see this video, comparing Gondor knights and Dol Amroth cavalry vs a clump of Uruk-hai.
Also, cav should avoid pikes to survive. Other implications of cavalry mechanics are if your enemy has too few pikes and you have enough cavalry, you can trample the same. Imagine a late game scenario with 6 Rohan exiles vs three Gondor swords and a pike. In total, we have 60 Rohirrim trampling 15 pikes and 45 swords. Considering the pikes are well positioned in front of the swords, the Rohirrim will lose 15 units to the pikes. But then, those 15 pikes will be on the ground, meaning the remaining swordsman are unprotected, and the remaining cavalry will demolish them. The Rohan player will have destroyed 3 swords battalions at the cost of maybe one battalion and a half. This means that to defend from big numbers of cav, you need enough pike battalions. Some pikes have the porcupine formation, which causes the cav to get stuck, and then protect your swords. Never charge cavalry through pikes in porcupine formation.
Some practical advice for microing cav:
- Use stances: Aggressive when trampling swords/archers. Defensive in most cases, as that will prevent your cavalry from automatically engaging enemy pikes if they enter they attack range.
- Avoid pikes, but be smart about it. While charging pikes directly is very bad idea, sometimes suffering one or two hits from pikes, if that allows to trample a high number of enemy swords, is worth. Also, carefully monitor the position of enemy pikes and try to trample any swords/archers that are not protected by them.
- Use cav to destroy weakened and/or retreating armies. After a battle, it is likely that your enemy has lost some (or even all) the pikes in his army, and your cav can quickly pick up those troops and finish them. Also, trampling from behind forces your opponent to stop retreating (pikes trampled from behind usually don't deal revenge damage), so your infantry army can keep killing the enemy.
- Sometimes the trample doesn't deal so much direct damage, but allows your own infantry to fight the enemy without receiving damage (as enemy units are on the ground). This is the case when fighting Imladris/elite armies, as the Imladris swords (as example) won't die quickly to the cavalry, but will be stopped in the ground and receive damage from your own infantry meanwhile, without being able to retreat nor deal damage.
- Cav is very good to kill isolated heroes (that is, heroes that are not protected by pikes). They can chase those heroes and surround them easily, dealing flank damage and taking them down quickly.
Trolls, werewolves and other monsters
While trolls and other monsters are classified as cavalry (thus, the same mechanics apply), they have different stats that modify the way they should be microed. As a general rule, monsters suffer more revenge damage than cavalry, and also deal less trample damage. That makes them much less suitable for direct trample maneuvers than cavalry. At the same time, they (unlike cavalry) deal AOE damage with knockback, which makes them better at melee fights. In melee, and thanks to the knockback, trolls can even do well against pikes (even if its not very efficient and should usually be avoided). Monsters (especially trolls) have two main uses: hit and run tactics (quickly destroying many enemy buildings and running away when pikes arrive), and army support (dealing damage in melee, protected by orcs, or stopping enemy cavalry, and also fighting enemy heroes, as they single target damage is high enough). As all fast units, they are also good at chasing retreating troops. To avoid them trampling enemy pikes and making sure they fight, most players micro trolls in battle in the following way: move near the enemy front line (never inside enemy clump, or flank damage will destroy them), press "s" (shortcut for stop, which ensures they don't actually trample), and put aggressive stance (so they attack automatically the closest enemies). Take into account that microing monsters in one of the most difficult things in the game and is very easy to lose them, especially if you lose track of them. As with cav, use defensive stance when they are not doing something to avoid auto trampling pikes or other units. Other monsters such as Werewolves, Mûmakil and to a certain extent Beorns in bear form, share the same micro principles, although their different speeds and armour/damage can change their utility.
Heroes are very powerful assets in your army, locked behind high resource cost, so careful micro can win (or lose) you the game. Heroes are strong but particularly vulnerable to flanking damage, so avoid being surrounded by any means, and try to protect them with pikes and swords. When microing heroes, I strongly advise to babysit at all times to ensure they don't run inside the enemy army and die (for some reason, they do it automatically). Also, use hotkeys for their powers (for much faster and efficient ability usage). A good way to keep all your heroes controlled is using the "o" hotkey that selects all heroes. That way, you can retreat them quickly or focus on an expensive enemy hero. Using defensive stance in normal battles can be a good idea since they one shot most troops anyway, so the damage decrease doesn't affect their performance, but the armor increase is useful. This also keeps them from charging without orders into enemy armies. Some heroes have especially long attack ranges and will auto attack far away enemies, so using defensive stance prevents that.