This article describes the components of Pathfinder 2e Monster AI. For the steps of making AI, please refer to separate article.

For the full content about Monster AI for Pathfinder 2e, please refer to the main page.

Table of Contents

• General Strategy
  • Adaptation
  • Target
  • Movement
  • Position
  • Optional keywords
  • Text description
• Special Tactics
• Basic Tactics
• Shortcut Syntax/Emoji

Monster AI – Components

The current version of Monster AI consists of 3 sections/components:

1. General Strategy
2. Special Tactics
3. Basic Tactics

General Flow

1. Start with Special Tactics section top to bottom
   
   Continue to next subsection until the monster’s all available turn actions for the monster are complete i.e. 1 action, move and +/- bonus action/reaction.
   
2. If Special Tactics section does not complete the monster’s turn, follow Basic Tactics section top to bottom.
   
   Refer back to general strategy section whenever appropriate e.g. look for default target, default movement or AI defined keyword etc.

If there are more than one option i.e. tie breaker is needed, a player/GM makes the choice based on the preferred difficulty level.

General Strategy

This section defines the general strategy of the monster. Usually, more specific so I call tactics are provided in following sections and that will override this section.

This section consists of following 5 entries:

1. Adaptation
2. 🎯(Target)
3. 📍(Position)
4. 👣(Movement)
5. Other notes

Adaptation

For detail of this section, please refer to the dedicated article written for D&D 5E version of Monster AI making.

The section specifies adaptation capability of the monster when encountering the target PC having immunity, resistance or weakness against the monster’s attack. I learned this during my own play with original version of Monster AI in 5E system not incorporating this element. Without this section, monsters kept hitting non-silver physical damage immune character without switching to spell attack or changing to another target. Basically, a paradigmatic example of low artificial intelligence.

This section will specify adaptation category and optionally order of adaptation.

Adaptation [Adaptation Category] [Adaptation Order]

Adaptation category

The category is determined based on the Monster’s intelligence ability score as detailed in the table below. The original table was developed for D&D 5E basing on the Monsters Know What They’re doing book/website.

The current version directly translated the intelligence ability score values to the equivalent modifier values as the Pathfinder 2E depicts monster stat block based on modifier values rather than actual ability scores.

The category defines presence of keyword that could trigger adaptation. For example, if a monster with immunity category adaptation attacks a target with “immunity” to its attack, it realizes something is not right and try to adapt. However, the same category monster attacks target with resistance to its attack won’t notice anything and just keep attacking.

The last two categories, “immunity, resistance, weakness” and “instant” are for monsters who have high enough intelligence so they will try to assess target’s vulnerability. If it finds one and able to use it against the target, it will do so as soon as possible.

The difference in two categories are the timing when they discover the weakness. The “instant” category monsters are so intelligent, it supposedly have a superpower to even find the hidden weakness. I interpreted this as to see the weakness immediately from the instance the monster sees its foe.

The “immunity, resistance, weakness” category monsters are intelligent enough to actively look for weakness but there is assessment period. I defined this as X turns based on the number of intelligence modifier where X is 6 – INT Modifier. If the monster has almost superpower level of intelligence, it takes only 6-4 = 2 turns. Whereas, if it has 2 intelligence modifier, it takes twice as long (6-2 = 4 turns).

Adaption order

When there is adaptation category and the monster has multiple types of attack options, one should specify adaptation order based on the strike types: melee (⚔️), ranged (🏹) or spellcasting (🪄).

Adaptation: Immunity, Resistance, Vulnerability | ⚔️ > 🏹 > 🪄

Order of adaptation

When adapt is triggered follow the order below.

1. Top to bottom in special tactics section entry for the failed attack’s action type.
2. Move to the highest available attack action type specified in the adaptation section
3. Switch target excluding the current and previously determined to be unable to damage target(s).

For example, if the target PC is immune to a specific type of ranged attack by monster who has Adaptation category of Immunity, the monster tries another ranged attack option that shows up top in the special tactics section if available.

If that’s also fails and there is no more ranged attack option, the monster moves to the next type of attack action option based on the adaptation order. Let’s say the order is ⚔️ > 🏹 > 🪄. In this case, the monster moves to melee (⚔️) attack as it is preferred over spellcasting (🪄).

Switch target

If all types of attack options are exhausted and none can damage the PC, it starts to search for alternative target. For the actual choice of another target, follow the regular target selection rule with failed target(s) excluded from the list.

🎯 closest > most wounded

🎯 most wounded  > closest

🎯 In 2 strides range > up to 2 other melee allies gather > closest

👣 Safest > shortest path

👣 Shortest > safest path

📍(shortbow) 30-40ft > Standard Cover
📍(retreat) stride max possible distance away from 🎯

1.📍(shortbow)
2. 🏹shortbow

Flee: Move away from target carefully i.e. use step if needs to. 

Flee:
  While in melee combat: step
  While actions available: stride away from target

Start by putting all quick traps (trap tactics). Then throw spears (ranged tactics). If all spears are consumed or PC reaches to this, shift to hit & run melee combat (basic tactics).

Special Tactics

This section defines trigger based response of the monster.

The general format is

While/At/If/When [Event/Condition/Trigger]

Detail of the actions

Example of event/trigger can be

• If HP < 3: Triggers if the monster’s hit point becomes less than 3.
• If in melee combat: Triggers if the monster is being involved in melee combat i.e. one or more foe is next to the monster
• If leader/boss is slayed: Triggers if the leader/boss is slayed.

Let’s take a specific examples.

If HP < 3:
    Flee

This means if the monster’s hit point reaches 2 or below, the monster flees.

At vs. If vs. When

I have decided to use “while”, “at”, “if” and “when” to differentiate the timing of the special tactics is being checked.

• At – Used when a very specific timing during the combat. E.g. At the beginning of this turn, At the beginning of the first round etc.
• If – This condition is checked during the monster’s own turn.
• When – This condition triggers as soon as the condition is met. This is useful for triggering reaction etc.

When it takes the first damage: 
    Do something!

In the example above, as soon as the Monster takes the first damage i.e. mostly during player’s character turn, the event triggers.

If it took the first damage:
     Do something!

This looks similar to the other but this is an “if” condition, so Monster checks this when its next turn comes.

While/Until

In 3 action system of Pathfinder 2e, loop type statement simplify AI writing.

• While/until – actions will continue until the condition is met. Both conditional words achieve the same result but one is more natural than another depending on the circumstance.

Until this reaches to 🎯: 👣(stride)
While this has not reached to 🎯: 👣(stride)

I prefer until statement in the above case.

While action is available:⚔️ jaws
Until all action is used up:⚔️ jaws

I prefer “while” statement in above case.

Subcategories

You can consider switch condition type format from programming language when applicable to keep the design cleaner.

In above case, it may be easier to see the specific condition check relates to low HP, but not specific enough. Under the category, there are two entries with each essentially having own if statement. If 3 or 4 HP: and if <=2 HP:.

Section

Sometimes, there is a block/subsection of tactics that are independent. Prototypical example is creatures that switch melee and ranged attack. Unless specific switching event occurs, these creatures use ranged or melee tactics independently.

This is defined with the section name and separator.

All the codes following below the separator is part of the given section. Switching one section to another section must be explicitly indicated.

If in melee combat:
	Swap to longsword (2 actions)
	Use melee attack tactics

Above is a code from ranged attack tactics section. The particular block of codes cover the situation when the monster is forcefully put into melee combat by PC.

After the end of the section, if 3 actions are not completed just as normal flow AI continues to basic tactics section. Designing soldiers are good example using this syntax.

Shortcut Emoji

One of key for designing good, usable monster AI is elegancy in the coding. As in computer programming, one can code AI in many different ways to do the same, but the preferred/better implementation is “simple/shorter” coding achieving the same. This is especially important as user of AI here is ourselves so we want to quickly identify exactly what section we should be reading.

Keyword/emoji aids visual skimming and cleaner code. I do recognize this creates a learning curve, familiarization to my monster AI format so I am trying to balance the use.

Followings are list of icons I currently use.

⚔️ = melee attack

🏹 = ranged attack

🪄= spell casting

🎯 = target

👣 = move/movement

% = Probability

📍= position

⬜ = Square (a grid space)

Single Line, multiple action

A ➡️ B = First perform A then B.

In contrast, A + B means A ➡️ B or B ➡️ A based on the situation.

This notation allows single line multi-step action writing.

Reserved action

1️⃣/2️⃣/3️⃣=First/second/third action.

This is specifically developed for Pathfinder 2E system. Its 3 action system allows new level of flexibility and tactic that was not possible in 5E system. Using with loop statement e.g. while, this allows cleaner coding and acts as reminder/flag to the user..

Specifically, this has been developed for hit & run tactics where the third action is usually reserved for retreat.

Coding this using just top to bottom order format, multiple scenario need to be covered. Move-Hit-Retreat, Hit-Hit-Retreat, Move-Move-Hit, Move-Move-Move, and Hit-Hit-Hit (when cornered). This approach will need at least couple if statements. Having reserved action, this could be simplified to single 4 line block.

Until this reaches to 🎯: 👣 (stride)
While
	3️⃣ If used ≥ 1 jaws & able to retreat:📍(retreat) 
 	⚔️ jaws

As a user of this AI, 3️⃣should get your attention but that only applies to the third action.

When reading the while loop section, and on the third action of the monster, you check the condition. It states at least one jaws strike has been used, so the monster won’t do move-move-retreat, which is clearly wrong thing to do.