The Official AI Topic.

[1% critted]

By popular demand, here are some of the quirks I know, general and specific. Anyone can add their own knowledge to the topic.

General:

-If the AI has a 1-2 range weapon, and your unit is adjacent to a positive terrain(woods, fort), it will go to the terrain and attack on one range instead of 2. Example: Avatar is adjacent to a forest and in range of a mage. Avatar has a thunder tome. The mage will move to the forest instead of attacking on range.

-If an enemy has counter, it will 1-range on purpose if the retaliation can kill you. This one has not been 100% proven, take it with a grain of salt.

-If you are blocking a path with a unit, and behind that one there is a unit that is on the verge of death, AND there is an enemy in front of the ally that's blocking the path, the enemy will move, and let a 2-range kill your weakened unit. Example: Lissa is behind Frederick on the Chapter 5 hill choke. The short axe barbarian is in range and can one shot Lissa. A Myrmidon is in front of Frederick. On Enemy phase the myrmidon will move, and let the barbarian kill Lissa.

-The AI takes into account crit chance. Example: There's a killer Axe barbarian that can kill a low-luck unit like Vaike with a crit. But Chrom has less defense but faces 0% crit. The barb will go for Vaike. Not 100% proven but has happened often enough for me.

-The AI takes into account possible hit chance over more damage. Example: Lon'qu with 5 def on a fort, a barbarian has 0% hit chance. Panne with 10 defense on a plain, The barbarian will go for Panne.

-The AI doesn't know it has activation skills. Example: If a Luna+ barb can kill a low health unit with a Luna+ activation, but it can deal more damage to a different, full health unit without the activation, it will go for the unit with higher HP.

- If the AI can attack an ally and an other unit, and the attack won't kill either, they will attack the other unit.

-The AI will rather double thru SPD than with a Brave weapon. (EG they have a Brave Sword and a Balmung. They have enough SPD to where they'll double your unit with the Balmung equipped, but not if they equip the BS. Assuming "standard enemy forge" on the BS, both have the same damage output but the enemy will pick to attack using Balmung.)

-The AI does indeed calculate for Brave attacks and WRBonus. They'll pick a Celica's Gale over Mjollnir. (11 x 2 over 20) ...they also calculate for weapons that give +[Offense Stat]... (Meaning the AI will use Valflame (18+5) over almost any other tome, except ****ing Waste)... However the AI does not calculate for -faire skills.

-Given a Rescue staff, the AI is extremely strange-- and will make awkward moves, that sometimes are sheer genius (Warp Counter SM to Squishy Mage), other times, incredibly dumb (Pull Rally Bot into fight).

-Given no weapons, an AI controlled unit will do the following: If allies remain who can fight/are armed: Attempt to flee to the corners of the map. If no allies can fight: Stand there and await the inevitable. This can potentially force a cat's game, should a flier reach an inaccessible part of a map (I.E. the lower right of Ch 7.) and the player has no Mire or Fliers to kill that unit.

(These were contributed by Airship_Canon, nice finds since I never streetpass and almost never spotpass battle.)

-The AI can calculate ahead a lot of moves. Especially if the combination of moves can kill one of your characters. If this combo is stopped by some reason or another(a miss, dual guard), the AI will go back to it's usual behavior of doing the most damage. (XeKr contributed this one)

-Like in FE12, the AI will move towards the direction of your most weakened unit. Unless there is a bridge or something that makes the area where said unit is unaccesible, they will move towards a spot where they can cross to that area.

Specifics:

Prologue: Second wave doesn't move until you are in range of one of the second wave enemies. The first wave is auto-aggroed.

Chapter 1: Whole map is auto-aggroed.

Chapter 2: Second wave won't move until you are in range of TWO enemy units of the second wave. First wave is auto-aggroed.

Chapter 3: Neither left or right side will move until you are in range of one of them. When you do get in range of one the other side will move. The two Knights behind the doors are independent and are only aggroed when you get in range of them. But if you get in range of one of the other enemies, the other knight will get aggroed. Once you get in range of the mercs/archers/fighters, either one of them on the upper level, the whole map is aggroed.

Chapter 4: Map is aggroed per turn: First turn, the nearest fighters and the mages. Second turn the knights. Third turn the Short axe fighters. Fourth turn Marth(Lunatic mode only). Any enemy can be aggroed if you get in their range.

Paralogue 1: The nearest barbs, archers and the nearest thief are all aggroed at the start. A thief will be moving for the killer lance chest starting on turn one. The two barbs in the room are aggroed when you put someone in the pillar or in range of both of them. The two barbs, archer and thief to the west are aggroed when you get in range of one of them. The remaining enemies are aggroed when in range and are independent.

Chapter 5: Everything is aggroed, some of the northern wyverns and the boss. Also in the not-aggroed are the barb, myrm and dark mage on the north. The dark mage is independent, but the other two are tied together.

Paralogue 2: All the barbs are going for the village. When it's destroyed they will all go for you. The mages and archers will attack you if you get on their range, regardless if the village is destroyed or not. The boss and his pack move 1 turn after the village is destroyed (need some confirmation on this.)

Chapter 6: The whole map is aggroed, Validar moves on turn 5 or 6 ( can't remember.)

Chapter 7: Wyverns are aggroed when you get in range of them. On turn 1, the northern mountain wyverns will move down, and the nearest infantry enemies will move. On turn 2, the second infantry pack will move. On turn 3, the final infantry pack will move and the other mountain wyvern will move. On turn 5, after the reinforcements appear, the rest of the map is aggroed, including the boss.

Paralogue 3: Most of the enemies that start near you are aggroed towards you. The fighter and archer to the left near the mountain too. The group to the right as well, except for the two knights, they will attack the villagers first. The pegasi, and the whole southwest group are moved individually and are aggroed individually. Boss moves in turn 5 or 6.

Chapter 8. Every enemy is aggroed from the start, except the dark mage + fighter combo near the left village(aggroed when in range of both) and the whole south pack (aggroed when in range of the killing edge myrmidon or when attacked).

Chapter 9: The map is divided in two(the starting vertical line that is the start, and the horizontal line where tharja and a lot of mooks are.) The first part of the map is aggroed automatically. The second part is aggroed when in range of one of the wyverns or the soldier, or when the reinforcements appear, in turn 5. (Thanks to Interceptor for the second part note.)

Paralogue 4. The enemies near Anna, and the enemies in the southern half of the map are all aggroed. The exception is the mage on the room with the large bullion. In the other half of the map the ranged units can be aggroed individually by getting in their range. All of the enemies in the middle room will be aggroed if the door is opened. The barbarian+mage combo in the killing edge room is aggroed when you get in the range of the barbarian. The mage in the arms scroll room is independent. The boss and his crew will move when you are in range of either the boss, or the mage.

Chapter 10. The enemies in the first, second and third passageways are aggroed immediately. The enemies in the norther portion of the map are aggroed when the reinforcements pop up in turn 3 or 4(can't be sure exactly). The exception to this are the two soldiers and the two barbarians nearest to the boss. The thieves escape through the passage behind the boss.

Chapter 11: All non reinforcement enemies are aggroed when reinforcements arrive, at turn 3. The exceptions to this rule are Gangrel's group, which are aggroed when you get in range of one of them, and the starting wyvern riders on turn one.

Chapter 12: The two groups with the paladin leaders move on turn one. The group with the Bow knight to the left moves on turn 2. The group with the bow knight to the right moves on turn 3. The groups on the boat move on turn 6, but they can be aggroed separately. Only the one on the right and the one to the left though.

Chapter 13: The group to the south is aggroed immediately, the ones in the near hills can be aggroed by getting in range. The group to the north moves on turn 3. Once the sniper reinforcements arrive in turn 5, every enemy is aggroed.

Chapter 14: Any enemy is aggroed when in range.The units nearest to the bridges start moving from turn one, same with the pegasi. On turn three the mages and cavs from the left move. On turn 5 the southern general moves. On turn 7 the other promos move.

Chapter 15: On turn 3 the mage group to the left starts moving(LM only.) On turn 4 the cavs and mages nearest to the boss move. On turn 7 the Dark knights and their group moves. (I'm not really sure of these ones feel free to correct them.)

Will update more at idk intervals of time. Feel free to correct any specifics.

Edited June 24, 2013 by 1% critted

[Aircalipoor]

-If an enemy has counter, it will 1-range on purpose if the retaliation can kill you. This one has not been 100% proven, take it with a grain of salt.

Warriors used they bows against my units. I had swordusers, who had a high avoid against axes and no 2 range.

Paralogue 2: All the barbs are going for the village. When it's destroyed they will all go for you. The mages and archers will attack you if you get on their range, regardless if the village is destroyed or not. The boss and his pack move 1 turn after the village is destroyed (need some confirmation on this.)

It is hilarious. I had a unit on the village(without visiting it) and all bandits ganged him up and only the southern one attacked my unit. I actually attacked the bandits with other units, but they ignored them completely, even if they could OHKO them.

[Airship Canon]

The AI will rather double thru SPD than with a Brave weapon.

(EG they have a Brave Sword and a Balmung. They have enough SPD to where they'll double your unit with the Balmung equipped, but not if they equip the BS. Assuming "standard enemy forge" on the BS, both have the same damage output but the enemy will pick to attack using Balmung.)

The AI does indeed calculate for Brave attacks and WRBonus. They'll pick a Celica's Gale over Mjollnir. (11 x 2 over 20) ...they also calculate for weapons that give +[Offense Stat]... (Meaning the AI will use Valflame (18+5) over almost any other tome, except ****ing Waste)... However the AI does not calculate for -faire skills.

Given a Rescue staff, the AI is extremely strange-- and will make awkward moves, that sometimes are sheer genius (Warp Counter SM to Squishy Mage), other times, incredibly dumb (Pull Rally Bot into fight).

Given no weapons, an AI controlled unit will do the following: If allies remain who can fight/are armed: Attempt to flee to the corners of the map. If no allies can fight: Stand there and await the inevitable. This can potentially force a cat's game, should a flier reach an inaccessible part of a map (I.E. the lower right of Ch 7.) and the player has no Mire or Fliers to kill that unit.

[Tamanoir]

Do someone have confirmation for Staff-only units ?

What is sure is that they will come for the most damaged unit (This must detailed to know if what is counted is the percentage of HP lost, or just less HP in general, I would say the later...) no matter what the distance. If no allied remains, they will stop moving.

They seems to act either first or last, but I don't know the details of this. I think they act first unless another unit can one shot a nearby ennemy (Tested on Lachesis' Spotpass team, and a heavily damged paldin attacked first because he could one shot Panne...)...

And obviously, all the Spotpass Team and Skirmish are auto-aggroed.

[darkkfan]

By popular demand, here are some of the quirks I know, general and specific. Anyone can add their own knowledge to the topic.

General:

-If the AI has a 1-2 range weapon, and your unit is adjacent to a positive terrain(woods, fort), it will go to the terrain and attack on one range instead of 2. Example: Avatar is adjacent to a forest and in range of a mage. Avatar has a thunder tome. The mage will move to the forest instead of attacking on range.

-If an enemy has counter, it will 1-range on purpose if the retaliation can kill you. This one has not been 100% proven, take it with a grain of salt.

-If you are blocking a path with a unit, and behind that one there is a unit that is on the verge of death, AND there is an enemy in front of the ally that's blocking the path, the enemy will move, and let a 2-range kill your weakened unit. Example: Lissa is behind Frederick on the Chapter 5 hill choke. The short axe barbarian is in range and can one shot Lissa. A Myrmidon is in front of Frederick. On Enemy phase the myrmidon will move, and let the barbarian kill Lissa.

-The AI takes into account crit chance. Example: There's a killer Axe barbarian that can kill a low-luck unit like Vaike with a crit. But Chrom has less defense but faces 0% crit. The barb will go for Vaike. Not 100% proven but has happened often enough for me.

-The AI takes into account possible hit chance over more damage. Example: Lon'qu with 5 def on a fort, a barbarian has 0% hit chance. Panne with 10 defense on a plain, The barbarian will go for Panne.

-The AI doesn't know it has activation skills. Example: If a Luna+ barb can kill a low health unit with a Luna+ activation, but it can deal more damage to a different, full health unit without the activation, it will go for the unit with higher HP.

- If the AI can attack an ally and an other unit, and the attack won't kill either, they will attack the other unit.

Specifics:

Prologue: Second wave doesn't move until you are in range of one of the second wave enemies. The first wave is auto-aggroed.

Chapter 1: Whole map is auto-aggroed.

Chapter 2: Second wave won't move until you are in range of TWO enemy units of the second wave. First wave is auto-aggroed.

Chapter 3: Neither left or right side will move until you are in range of one of them. When you do get in range of one the other side will move. The two Knights behind the doors are independent and are only aggroed when you get in range of them. But if you get in range of one of the other enemies, the other knight will get aggroed. Once you get in range of the mercs/archers/fighters, either one of them on the upper level, the whole map is aggroed.

Chapter 4: Map is aggroed per turn: First turn, the nearest fighters and the mages. Second turn the knights. Third turn the Short axe fighters. Fourth turn Marth. Any enemy can be aggroed if you get in their range.

Paralogue 1: The nearest barbs, archers and the nearest thief are all aggroed at the start. A thief will be moving for the killer lance chest starting on turn one. The two barbs in the room are aggroed when you put someone in the pillar or in range of both of them. The two barbs, archer and thief to the west are aggroed when you get in range of one of them. The remaining enemies are aggroed when in range and are independent.

Chapter 5: Everything is aggroed, some of the northern wyverns and the boss. Also in the not-aggroed are the barb, myrm and dark mage on the north. The dark mage is independent, but the other two are tied together.

Paralogue 2: All the barbs are going for the village. When it's destroyed they will all go for you. The mages and archers will attack you if you get on their range, regardless if the village is destroyed or not. The boss and his pack move 1 turn after the village is destroyed (need some confirmation on this.)

Chapter 6: The whole map is aggroed, Validar moves on turn 5 or 6 ( can't remember.)

Chapter 7: Wyverns are aggroed when you get in range of them. On turn 1, the northern mountain wyverns will move down, and the nearest infantry enemies will move. On turn 2, the second infantry pack will move. On turn 3, the final infantry pack will move and the other mountain wyvern will move. On turn 5, after the reinforcements appear, the rest of the map is aggroed, including the boss.

Will update the OP at a later time, I'm tired.

Nice job making this topic, I should have done it myself but I was too lazy. Plus, there seems to be a trend lately where if I discuss doing something but am too lazy to do it, someone else will do it anyway.

Aside from the thing about counter kamikazees with 1-2 range options, I've had it go both ways so I suppose there is no objection to what you have posted about it. For chapter 5 you might want to mention that the northern group is aggroed separately from the group that moves initially, although you might already have it and perhaps I am just misinterpreting you.

In any case, this should certainly be helpful and it looks pretty accurate so far. I will help contribute with what I find on Luna+, but keep up the good work.

Edited June 16, 2013 by Walhart

[XeKr]

I'm fairly certain many AI movements/pathing have an RNG component. If enemies are aggro'd but cannot reach your units that turn, they seem to randomly decide betweeen any of the possible pathings that result in being around the same number of tiles away from your units (Can be observed as early as the first Mage in Prologue). If they can attack, they seem to decide randomly from which tile to attack from (unless it's a terrain thing, which they definitely prefer)

In choosing between attacking 2 characters, I'm not actually sure how much it's weighted by your character durability and such as well. It does seem weighted in many cases (more likely to attack weaker units), but I have also observed the AI attacking strong units like Frederick over weak ones. It doesn't seem as set as FE12, for example.

It seems strange that they would take advantage of Counter and not Luna+. It's possible, but would be quite strange programming. Given others reporting the opposite happening, I'm inclined to think it's a random thing.

Might comment on aggro behavior for a few other chapters later.

EDIT: I'll also note the AI in general is very good at calculating if something can kill. They really like to team up in combination if that said combination can kill a unit. Also, Boss units tend to move first on their turn (preventing EP exp), unless another enemy can kill one of your units.

Edited June 16, 2013 by XeKr

[Redwall]

I'm fairly certain many AI movements/pathing have an RNG component. If enemies are aggro'd but cannot reach your units that turn, they seem to randomly decide betweeen any of the possible pathings that result in being around the same number of tiles away from your units (Can be observed as early as the first Mage in Prologue).

This may or may not be explained by the amount of damage your units have taken. In my five-turn clear of Lunatic C3, I needed a Fighter to hit my lance-wielding Frederick for the enemy positioning to go my way. Have you tested the Prologue Mage movements while accounting for the damage sustained by Frederick?

[1% critted]

Oh yeah, like in FE12, the AI will move towards the direction of your most weakened unit. Unless there is a bridge or something that makes the area where said unit is unaccesible, they will move towards a spot where they can cross to that area.

[shadowofchaos]

-If the AI has a 1-2 range weapon, and your unit is adjacent to a positive terrain(woods, fort), it will go to the terrain and attack on one range instead of 2. Example: Avatar is adjacent to a forest and in range of a mage. Avatar has a thunder tome. The mage will move to the forest instead of attacking on range.

Wait wait wait wait. Wouldn't that be obvious in that situation? Considering that they'll take a counterattack anyway from the thunder tome?

I don't remember exactly, but what would they do if MU was say... equipped with a Killing Edge instead? I'd think they'd go for the "no counterattack" option and attack from range?

[XeKr]

This may or may not be explained by the amount of damage your units have taken. In my five-turn clear of Lunatic C3, I needed a Fighter to hit my lance-wielding Frederick for the enemy positioning to go my way. Have you tested the Prologue Mage movements while accounting for the damage sustained by Frederick?

True enough. I haven't tested that, though I would if I had the save slots. Someone should test though. >_>

I know that AI decision-making in deciding which tile/direction to attack from is random (as in my C1 Turn 1). Along the same lines, I would expect pathing to be random in general. It's also hard for me to envision the type of programming that would choose between 2 seemingly identical pathings, based on damage. Frederick is the only unit close to the Mage, so I don't see an immediate difference in which way the Mage moves.

It should be fairly easy to test, as the Barbs have high hit rates and the Myrms do 0 damage.

Wait wait wait wait. Wouldn't that be obvious in that situation? Considering that they'll take a counterattack anyway from the thunder tome?

I don't remember exactly, but what would they do if MU was say... equipped with a Killing Edge instead? I'd think they'd go for the "no counterattack" option and attack from range?

In my experience, they prefer going on good terrain over avoiding counterattacks.

[shadowofchaos]

In my experience, they prefer going on good terrain over avoiding counterattacks.

http://www.youtube.com/watch?v=_Bd2PzFRmdE

So if it was only one fort, that would mean they'd go for that instead?

Time to test this.

Edited June 16, 2013 by shadowofchaos

[XeKr]

Yes, though there may be more factors like the damage they can do, the damage you do to counter, their Hp, your Hp, etc.

[riariadne]

I'm pretty sure enemies will avoid triggering Counter if you have it and they can attack from 2 range. I didn't test this much, so I could be wrong.

[shadowofchaos]

Yes, though there may be more factors like the damage they can do, the damage you do to counter, their Hp, your Hp, etc.

Might have to test this with not super broken Olivia then.

http://www.youtube.com/watch?v=wJjRpphCqyc

[HadouKirby]

I don't think anyone mentioned this, but the A.I. tends to try use the weapon triangle to its advantage. Like, if a soldier can choose to attack a mage or a mercenary, it'll usually attack the mercenary.

[XeKr]

Might have to test this with not super broken Olivia then.

http://www.youtube.com/watch?v=wJjRpphCqyc

There's also the possibility that boss AI differs from specific enemy AI. Regardless, iirc, I have seen cases where the AI could avoid counterattack damage but chooses to eat the counter instead.

Did you test that more times? 2 is a low sample size. It would definitely tell us something if Gangrel always attacked from that square in that circumstance. At the very least, less RNG than expected.

Edited June 16, 2013 by XeKr

[Scarlet]

Related to its ability to plan ahead moves, consider this scenario:

One of your units is in range of multiple enemies, but there are less spots to attack that unit from than there are enemies in range. However, some of these enemies are likely/guaranteed to survive your unit's retaliation, while some of them are likely/guaranteed to die. If these enemies could potentially kill your unit given more attacks than the bulky enemies can provide, it will purposely suicide the less durable enemies on your unit just to damage it enough to kill.

It should also be noted that AI behaviour per chapter can differ depending on the difficulty. The behaviours currently listed in the OP seem to apply to Lunatic; on lower difficulties, some waves of enemies have more lenient conditions to become aggro'd. For instance, I'm pretty sure that chapter 4 Marth, on Normal and Hard mode, will only move if one of your units is in his range.

[riariadne]

For instance, I'm pretty sure that chapter 4 Marth, on Normal and Hard mode, will only move if one of your units is in his range.

I don't remember this being true for HM?

[Meteor]

Marth won't auto-aggro on Hard. I play that mode almost exclusively.

[Scarlet]

I don't remember this being true for HM?

Maybe just Normal mode, but I distinctly recall being able to just stare at him for several turns in one of my playthroughs without him feeling like coming my way at all, until I eventually made the first move.

[1% critted]

Yeah all of the aggros I listed are based on lunatic mode, since that's the only mode I play.

Thanks, shadowofchaos, for those tests since I can't test anything myself for now sadly. And for also providing video footage!

OP updated with more Specifics.

[Scarlet]

Yeah all of the aggros I listed are based on lunatic mode, since that's the only mode I play.

You may want to note that in the OP, then, just to avoid confusion.

[1% critted]

I'm going to start pointing out which ones I know are only for Lunatic mode. If someone could check the ones in hard, I will update accordingly. I don't have the game right now so I can't test anything myself.

[JSND Alter Dragon Boner]

What if the AI has 1% critical chance?

[1% critted]

What if the AI has 1% critical chance?

Then you miss twice with 99% and you get critted and die. Weeeeeeeeee