How does the AI work for a Witch Doctor's summoned pets?

I'm mostly curious about how they'll prioritize their actions. Will they just attack the first target they see, attack the target their summoner is, attack targets attacking them, attack targets attacking their summoner, or something along those lines? Do certain pets prioritize certain actions over others? For example, will some pets prioritize trying to keep things from punching their summoner versus trying to do damage to something?

Solution 1:

I went ahead and ran some tests on this myself because I really wanted to know how exactly the mechanics appear to work.

Method: I tested in Act 1 Hell with my weapon unequipped so my pets would be out for the longest time and not just kill everything. I tested for every summoned creature that had an offensive ability. I used no runes for the abilities themselves, and only used passives that increase the health and defenses of the pets (so they wouldn't just fall over). I tested if they'd assist their summoner in killing a target by punching enemies in the face with my weapon uneqipped and seeing if their behavior changed. I tested if they'd assist their summoner if he got low health by letting a creature beat on me while the pet beat on something else and seeing if their behavior changed.

Findings:

Gargantuan appears to:

• Attack the closest enemy, regardless if the enemy is attacking him.
• Change targets only when an enemy becomes closer to him than the one he is hitting.
• Not assist his summoner when the summoner is attacking a specific target.
• Not assist his summoner when the summoner is being punched in the face.
• Not change his behavior when the summoner becomes low on health.

Zombie Dogs appear to:

• Attack the closest enemy, regardless if the enemy is attacking them.
• Change targets only when an enemy becomes closer to them than the ones they are already hitting.
• Not assist their summoner when the summoner is attacking a specific target.
• Not assist their summoner when the summoner is being punched in the face.
• Not change their behavior when the summoner becomes low on health.

Corpse Spiders appear to:

• Attack the closest enemy to their point of summon (the place you throw them).
• Change targets only when an enemy becomes closer to them than the one they are already hitting
• Not assist their summoner when the summoner is attacking a specific target.
• Not assist their summoner when the summoner is being punched in the face.
• Not change their behavior when the summoner becomes low on health.

Hex Ability's Fetish Shaman appears to:

• Polymorph the closest enemy to his point of summon (on top of the caster when the ability is used).
• Polymorph the closest enemy that is not polymorphed already.
• Not assist his summoner when the summoner is being punched in the face.
• Not change his behavior when the summoner becomes low on health.
• Note: I did not test for assisting on attacking a specific target with the Fetish Shaman because he doesn't actually deal damage, and I didn't test if he changed targets because he doesn't actually attack stuff.

Fetish Army appears to:

• Attack the closest enemy to their point of summon (around the caster when the ability is used).
• Sporadically run away from targets and/or change targets in what appears to be a completely random manner.
• Not assist their summoner when the summoner is attacking a specific target.
• Not assist their summoner when the summoner is being punched in the face.
• Not change their behavior when the summoner becomes low on health.

General findings broken down:

• Persistent pets (Gargantuan and Zombie Dogs) appear to attack the closest enemy in a Screen + 1/2 range until nothing is left or they die.
• Non-persistent pets (Corpse Spiders, Hex Ability's Fetish Shaman, and Fetish Army) appear to attack the closest enemy to their point of origin until nothing is left or their duration expires.
• All pets appear to only change targets if another target becomes closer to them than the previous one. This is only not true when a) the closer enemy is already surrounded by pets, b) the Fetish Army who will sometimes randomly change targets, or c) the Hex Ability's Fetish Shaman has already Hexed the target so targets the next closest.
• No pets appear to assist their summoner in any way due to any specific condition. They won't help against the target he is attacking if it is different to the one they are, they will not assist the summoner when something is beating on the summoner, and they won't assist the summoner when the summoner becomes low on health. If they're already summoned they will specifically target the closest enemy to them. The only way to get them to assist on a specific target would be to summon them closest to that target.