once the ais have any enemies in their danger zone, they will enter the aggressive stance and start to engage your troops. Their targeting priorities are determined by a few laws. These laws are considered in order. For example, a target that has the highest priority in law 1 will always override the priorities from other laws. The following laws are only considered if multiple troops have the same priority in all previous laws. For aoes, the ai will try to hit as many as possible, and will not use aoes against ST unless in very specific cases, not really much to talk about here.

Note: ai disregards any form of guard when deciding priorities

Law of Preparation:

AIs will always take defensive actions over offensive actions. This includes: guarding as many allies that are in the danger zone of enemies as possible, healing a low hp ally (emphasis on low hp).These actions will almost always happen before any offensive abilities. But are randomized between itself, for example, liana have an equal chance of casting prayer or heal no matter how many other allies with almost no hp exist. Buffing skills are very interesting cuz they seem to share priorities with offensive abilities like aoes and fireballs(need more confirmation). However, any skills have priority over normal attacks. If they can use a skill, they will use it.

Law of Killsteal(need further testing):

(Update: this law may have been removed in recent patches)
AIs want you dead, and the best way to do it is by knocking out one of your troops permanently from the map. If the ai think they can score a kill on someone, they will always target that troop(some people think this law exists, so I’ll just put it here, but I’ve never managed to successfully emulate a situation that an AI goes for a low hp target. Partially cuz it’s very hard to get a hero low enough when you don’t know what is considered low enough.)

Law of Counters:

AI will always try to attack the troop that it counters the most. For each enemy in range, the AI have a score depending on counter statistics: (O for own, E for enemy, H for hero, S for soldiers)

OS counters ES: 1; ES counters OS: -1;
OS counters EH: 1; EH counters OS: -1;
OH counters ES: 1; ES counters OH: -1;
OH counters EH: 1; EH counters OH: -1.

In the end, the score is compared and if there is a target with a higher score than anyone else. That will be the target attacked. For example an infantry hero with infantry soldier (A) will consider a lancer hero with lancer troop (B) with the score 4, and a cav hero cav soldier (C) with the score -4. This makes A favor attacking B a lot but really does not want to attack C. Do note that this implies A will have a score of 0 against both a flier hero with flier troops and a lancer hero with cavalry troops, and will have no preference between these 2 targets from this law.

Notes:

• Melee weakness of ranged troops is not accounted for here.
  
• Even if soldiers does not actually participate in combat, they still take part in the calculation. For, example an ai tiaris with Templar knights are extremely reluctant to attacking ai lancers even tho the Templar knights will not even get countered. However, the exception to this is if your soldiers are all dead. For example, while infantries are really happy to attack a hero elwin with phalanx. As soon as the phalanx are all dead, they lose interest in elwin.
  
• Although having killer equipments like slayer’s emblem make a “strong” icon show up when you are fighting against fliers, the AIs does not give a shit about it. It will not dissuade any fliers from ramming into you or make you more likely to attack enemy fliers. Similarly, Lance’s, paladins and Templar knights does not work when targeting priorities are considered (have not tested listell’s but I’d guess it works similarly)
  
• Skills with bonus dmg against certain advantage against specific enemy types is also disregarded. In fact, if you have frost strike and fireball, AIs actually have an equal chance of using either skill against a lancer.

Law of Weak Retaliation:

Enemies with ranged attacks will prefer attacking melee troops while an enemy with melee attacks will prefer attacking ranged troops(more specifically, troops with melee weakness). Sounds simple enough, or is it?

Notes:

• NO, it really isn’t.
  
• Almost everything is disregarded, as long as there is a ranged unit in a troop, may it be hero or soldier, it is considered to be ranged by AIs and AIs have no preference between them. EMB, samurais, Layla talent? All disregarded. Troops with particularly long-range (lana, catapult, ullr’s bow) will still prioritize melee enemies over 2 range enemies (preference between 2 range and 3 range to be tested).
  
• However, there is one exception. When you combine holy with non-holy unit types in a single troop, AI demon type troops become EXTREMELY confused. If they face two of these at the same time, they completely disregard this law.
  
• If you don’t know this before, skills have melee penalties as well. For example, shadow raid is considered to be a ranged skill and therefore have a melee penalty. This melee penalty overrides normal unit penalties, so if you attack with shadow raid as dragon master Cherie in melee, she still gets the 30% dmg melee penalty and only your melee troops will be dealing normal dmg. The good part about this is ranged units can actually use melee skills to eliminate their melee penalties. For example, a grand master Cherie still deals full dmg when attacking with lightning in melee range. Although if you use ambusher troops, her troops will suffer the melee penalty.(remove melee penalty effect like EMB, samurais and Layla overrides this penalty) So what does this have to do with the law?
  
• Well, when a melee troop is using a ranged skill, the AI will actually use the pattern of ranged troops instead. And vice versa. You can tell the type of attack from which class gives them most of the time. But, there are a few very particular cases. For example, air slash(Matthew, Kirikaze), javelin(Lanford) and discipline(Chris) are all ranged skills with no melee penalty. HOWEVER, Chris’ other skill, redemption, although seemingly identical with discipline, is actually a melee skill. When she uses redemption, she will prioritize ranged troops instead of melee ones. Moreover, because AIs love attacking at the longest range, she will try to attack in range against ranged enemies.
• This law is only applied to targets that have the highest priorities in the previous laws. A skeleton mage would rather die to an archer than attack a melee holy type.
  

Law of Least Distance:

when all of the above still can’t find a suitable target, the ai goes for the closest target.

Notes:

• This law is only applied to targets that have the highest priorities in the previous laws.
  
• Really not much to talk about here, whomever is the closest in tiles gets hit, end of story.

Law of Coordinates:

If there are multiple targets that are identical in all laws above. The AI establishes a coordinate system with itself as the origin, top as the positive y axis and right as the positive x axis. The AI will target the enemy with the largest x coordinate. If two units share the same x coordinate, AI targets the one with smaller y coordinate.
For example, here's the targeting order of an AI's target priority order within 2 tiles. the lower the number, the higher priority the unit within that tile gets hit.

Note:

• If you don’t know what the stuff above means, look it up. It’s middle school maths, not that hard.
• This law is only applied to targets that have the highest priorities in the previous laws.
  

a few words at the end

This is only a general rule. Some different enemies have very different targeting priorities. For example Ice dragon's ice age will target a unit at position 12 over position 8 etc.
Most of these are based on personal testing. With some rumors that I can't really test mixed in.
if you think one of these laws are wrong, please test it and let me know. Some of these I am not 100% percent confident and are somewhat tricky to test.
If you want to discuss in game mechanics with me, you can find me (Knighthelm of Baldea) in Eden's or the official discord channel