Author: nihil, hobbitdur

FF8 monster battle scripts are divided into 5 sections, init, turn, counter, death and pre-counter.
Each section contains code that is executed at different times during the battle.

Init: executes once when the monster is loaded into battle.
Turn: executes once the monster’s ATB bar fills. This happens after the monsters turn counter is incremented.
Counter: executes when the monster is targeted by a battle command.
Death: executes when the monster’s HP reaches 0 or it is afflicted with the Death status. (Eject may not trigger this section - this needs further testing.)
Pre-Counter: similar to counter but executed before it. Needs further testing. Seems to be used mostly for checking if the monster has the Death status and then change its animation. Ifs, variable assignments and stat changes can also be used. Launching an attack from this section crashes the game.

The order of execution when a monster is attacked is: pre-counter -> death (if killed) -> counter.
Note: pre-counter code will ONLY be executed after an attack that kills a monster if the monster’s death section has code in it (apart from “return”).
Note: if the death section is empty, it will function like a die opcode.
Note: if the death section is empty, it is mandatory for it to eventually execute a die opcode, otherwise the monster will continue fighting, even on 0 HP, making the battle unwinnable for the player and forcing them to run.
If running is not an option, this results in a soft lock.

Opcodes

Opcodes

Monster AI sections are composed of one-byte opcodes, each followed by a variable number of the bytes used as parameters.
These opcodes define the monster’s behaviour in battle.
Note: descriptions are written from the monster’s perspective, so “opposing party” refers to the party of playable characters.

Opcode 0x00 (0) - return

Summary

Opcode	IfritAI name	Size	Short Description
0x00	return	1	End monster’s turn

This opcode is used to end the monster’s turn, preventing further execution of code.
It is mandatory for every battle script section to end with a return.

Parameters

None

Opcode 0x01 (1) - print

Displays a battle message.

Summary

Opcode	IfritAI name	Size	Short Description
0x01	print	2	Print text

Parameters

Position	Size	Name	Type	Short Description
1	1	TextID	int	The index of the text

Texts are defined in section 7 of c0mxxx.dat files.
Each text has an ID, starting from 0 and incrementing with each subsequent text.
TextID corresponds to this ID.
Note that battle message speed is ignored.

Opcode 0x02 (2) - if

Summary

The if opcode allow to execute code only on certain condition

Opcode	IfritAI name	Size	Short Description
0x02	if	1	Define condition

Parameters

The if opcode is a really complex one with lots of different possibilities.
It is composed of a subject that define how the other parameters are used.
Then it uses 3 parameters for the condition: the left part of the condition, the right part, and the comparator.
So it does something like this: [ConditionLeftPart] [Comparator] [ConditionRightPart], for ex: COMBAT SCENE == 76
Then there is a jump param to define the jump size if the condition is not met

Position	Size	Name	Type	Short Description
1	1	SubjectID	SubjectID	Define what the if will be about
2	1	ConditionLeftPart	Vary	The left condition
3	1	Comparator	Comparator	The comparator of the condition
4	1	ConditionRightPart	Vary	The right condition
5	1	Padding	Unused	Always 0x00 (changing it has no impact)
6	2	Jump	int	The number of byte to jump if the condition is false

SubjectID

General info

The SubjectID defines what will be the type of the left part and right part of the condition
The Short text is a description of the subject id.
The Left text is the meaning of the ConditionLeftPart. {} is to be replaced with the value hold by ConditionLeftPart depending of Param left type
The Param left type define the type to use to translate the ConditionLeftPart
Same logic for the ConditionRightPart
The Param list can feed the param type with additional info.

Subject list

SubjectID	Short text	Left text	Param left type	Right text	Param right type	Param list
0	HP OF SPECIFIC TARGET	HP_SPE of {}	target_advanced_specific		percent
1	HP OF GENERIC TARGET	HP_GEN of {}	target_advanced_generic		percent
2	RANDOM VALUE	RANDOM VALUE BETWEEN 0 AND {}	int_shift		int	[-1]
3	COMBAT SCENE	COMBAT SCENE			int
4	STATUS OF SPECIFIC TARGET	STATUS_SPE OF {}	target_advanced_specific		status_ai
5	STATUS OF GENERIC TARGET	STATUS_GEN OF {}	target_advanced_generic		status_ai
6	NUMBER OF MEMBER	NUMBER OF MEMBER OF {}	target_advanced_generic		int
9	ALIVE	ALIVE			target_advanced_specific
10	ATTACKER	ATTACKER	subject10		complex
14	GROUP LEVEL	GROUP LEVEL OF {}	target_advanced_generic		int
15	ALIVE IN SLOT	ALLY IN SLOT {}	int_right	ALIVE	alive
16	GENDER CHECK	AT LEAST ONE ENEMY ALIVE HAS GENDER			gender
17	GFORCE OBTAINED	Gforce to be stolen	const	Not yet stolen	const	[200, 204]
18	ODIN OBTAINED	{} POSSESS ODIN	target_advanced_generic		int
19	COUNTDOWN	COUNTDOWN			int
20	STATUS OF ALL IN TEAM	STATUS OF ALL IN {}	target_advanced_generic		status_ai
>20	Var	var	var_name		int

If the SubjectID is > 20, it means the subject is of type var, the ConditionLeftPart is the ID of the var and the ConditionRightPart the value of the var to be compared

Additional info:

Here are additional info for some values

HP OF SPECIFIC TARGET

The ConditionLeftPart 0xCB (203) is persists across battles

Byte #1: 0x00 (Self / Last command user) or 0x01 (Any ally / opponent)
Byte #2:
- 0xC8 (200): Own HP / Any opponent’s HP
- 0xC9 (201): Unused / Any ally’s HP
- 0xCB (203): Last command user’s HP (persists across battles) / Unused
Byte #4: Remaining HP percentage
- 0x0A (10) = 100%
- 0x09 (9) = 90%
- . . .

2. Random Number Check

Byte #1: 0x02
Byte #2: Exclusive upper bound of range (0 to this value - 1)
Byte #4: Number to compare against

3. Status Check

At least 1 member:

Byte #1: 0x04 (Self / Last command user) or 0x05 (Any ally / opponent)
Byte #2:
- 0xC8 (200): Self / Any opponent
- 0xC9 (201): Unused / Any ally
- 0xCB (203): Last command user / Unused
Byte #4: Status ID

All members of party:

Byte #1: 0x14 (20)
Byte #2:
- 0xC8 (200): Opposing part
- 0xC9 (201): Own party
Byte #4: Status ID

4. Alive Count Check

Byte #1: 0x06
Byte #2:
- 0xC8 (200): Opposing party
- 0xC9 (201): Own party
Byte #4: Number to compare against

5. Specific Entity Alive Check

Byte #1: 0x09
Byte #2: 0xC8 (Unused?)
Byte #4: Entity ID

6. Last Action / Turn Count Check

Byte #1: 0x0A (10)
Byte #2:
- 0x00: Damage Type (Byte #4: 0x00 = Physical, 0x01 = Magical)
- 0x01: Last command user ID (Byte #4 = Entity ID)
- 0x02: Turn Counter that increases as soon as the ATB bar is full (Byte #4 = Number)
- 0x03: Command (Byte #4: 0x01 = Attack, 0x02 = Magic, 0x04 = Item, 0x06 = Draw, 0xFE = GF)
- 0x04: ID (Byte #4: Magic/Item/GF ID)
- 0x05: Element (Byte #4 = Element ID)
- 0xCB (203): Last command user party (Byte #4: 0xC8 = Own part, 0xC9 = Opposing party) TO BE TESTED

7. Entity Alive Check (In specific slot)

Byte #1: 0x0F (15)
Byte #2: 0xC8 (Unused?)
Byte #4: Target slot + 3 (e.g., 0x03 for slot 0)

8. Sex check

Byte #1: 0x10 (16)
Byte #4:
- 0xCA (202): Male
- 0xCB (203): Female

9. GF Check (Not yet obtained)

Byte #1: 0x11 (17)
Byte #2: 0xC8 (Unused?)
Byte #4: 0xCC (204)

10. Odin Acquisition Check (true if obtained)

Byte #1: 0x12 (18)
Byte #2: 0xC8 (Unused?)
Byte #4: 0x00 / 0x01 (true / false)

11. Timer Check

Byte #1: 0x13 (19)
Byte #2: 0xC8 (Unused?)

12. Variable Check

Byte #1: Variable ID
Byte #2: 0xC8 (Unused?)
Byte #4: Value to compare against

Opcode 0x04 (4) - target

Summary

This opcode defines a target, it must be used before any opcode that requires a target (like launching an ability).
If the target is a specific playable character who isn’t currently targetable, the character in the slot of the original target -1 will be targeted, if the original target was slot 0, the new target will be slot 1 instead.
Note that the original target will still be targeted by opcodes draw and blowAway.

Opcode	IfritAI name	Size	Short Description
0x04	target	2	Print text

Parameters

Position	Size	Name	Type	Short Description
1	1	Target	TargetBasic	The target

Opcode 0x05 (5) - die

Summary

Causes monster that executes this opcode to die.

Opcode	IfritAI name	Size	Short Description
0x05	die	1	Causes monster to die

Parameters

None

Opcode 0x0B (11) - useRandom

Summary

Picks one of 3 abilities to use randomly, then uses it.
Requires target to have been used.

Opcode	IfritAI name	Size	Short Description
0x0B	useRandom	4	Use random ability between 3

Parameters

Position	Size	Name	Type	Short Description
1	1	MonsterLineAbility1	MonsterLineAbility	The first ability line
2	1	MonsterLineAbility2	MonsterLineAbility	The second ability line
3	1	MonsterLineAbility3	MonsterLineAbility	The third ability line

Opcode 0x0C (12) - use

Summary

Use one ability, requires target to have been used.

Opcode	IfritAI name	Size	Short Description
0x0C	use	2	Use one ability

Parameters

Position	Size	Name	Type	Short Description
1	1	MonsterLineAbility	MonsterLineAbility	The ability line

Opcode 0x0E (14) - var

Summary

Sets local variable that will be only accessible by this monster during the battle.

Opcode	IfritAI name	Size	Short Description
0x0E	var	3	Set local var to specific value

Parameters

Position	Size	Name	Type	Short Description
1	1	Var	LocalVar	The var to store the data
2	1	Value	int	The value var is set to

Opcode 0x0F (15) - gvar

Sets global variable (accessible by all monsters).

Summary

Sets global variable (accessible by all monsters)

Opcode	IfritAI name	Size	Short Description
0x0F	gvar	3	Set global var to value

Parameters

Position	Size	Name	Type	Short Description
1	1	Var	LocalVar	The var to store the data
2	1	Value	int	The value var is set to

Opcode 0x11 (17) - svar

Summary

Sets savemap variable (not sure how it it stored).

Opcode	IfritAI name	Size	Short Description
0x11	svar	3	Set savemap var to value

Parameters

Position	Size	Name	Type	Short Description
1	1	Var	SavemapVar	The var to store the data
2	1	Value	int	The value var is set to

Opcode 0x12 (18) - add

Summary

Adds value to local variable that will be only accessible by this monster during the battle.

Opcode	IfritAI name	Size	Short Description
0x12	add	3	Add value to local var

Parameters

Position	Size	Name	Type	Short Description
1	1	Var	LocalVar	The var to store the data
2	1	Value	int	The value to add to the var

Opcode 0x13 (19) - gadd

Summary

Adds value to global var (accessible by all monsters).

Opcode	IfritAI name	Size	Short Description
0x13	gadd	3	Add value to global var

Parameters

Position	Size	Name	Type	Short Description
1	1	Var	GlobalVar	The var to store the data
2	1	Value	int	The value to add to the var

Opcode 0x15 (21) - sadd

Summary

Adds value to savemap var (not sure where it is stored).

Opcode	IfritAI name	Size	Short Description
0x15	sadd	3	Add value to savemap var

Parameters

Position	Size	Name	Type	Short Description
1	1	Var	SavemapVar	The var to store the data
2	1	Value	int	The value to add to the var

Opcode 0x16 (22) - recover

Summary

Sets remaining HP to max HP.

Opcode	IfritAI name	Size	Short Description
0x16	recover	1	Sets remaining HP to max HP

Parameters

None

Opcode 0x17 (23) - setEscape

Summary

Allows/Disallows escaping in the current battle.

Opcode	IfritAI name	Size	Short Description
0x17	setEscape	2	Sets ability to escape

Parameters

Position	Size	Name	Type	Short Description
1	1	EscapeActivated	Bool	True to allow escape, False to deactivate

Opcode 0x18 (24) - printSpeed

Summary

Displays a battle message, respecting the battle message speed setting.

Opcode	IfritAI name	Size	Short Description
0x18	printSpeed	2	Print text with battle message speed setting

Parameters

Position	Size	Name	Type	Short Description
1	1	TextID	int	The index of the text

Texts are defined in section 7 of c0mxxx.dat files.
Each text has an ID, starting from 0 and incrementing with each subsequent text.
TextID corresponds to this ID.

Opcode 0x1D (29) - leave

Summary

Makes the monster in a specified encounter slot leave combat.

Opcode	IfritAI name	Size	Short Description
0x1D	leave	2	Makes a monster leave combat

Parameters

Position	Size	Name	Type	Short Description
1	1	Target	int	Monster that’s made to leave

Target is the slot in which the monster currently is in the fight.
Note that if 200 is used, the monster executing this opcode will be used as Target.

Opcode 0x1F (31) - enter

Summary

Makes the monster in a specified encounter slot enter combat, by setting it’s Enabled, NOT Targetable and NOT Loaded flags to true.
Whilst possible, it is not advisable to use enter on an encounter slot if the monster in that slot is currently in the fight.

Opcode	IfritAI name	Size	Short Description
0x1F	enter	2	Makes a monster enter combat

Parameters

Position	Size	Name	Type	Short Description
1	1	Target	int	Encounter slot of the monster

Target is the monster’s encounter slot, as defined in scene.out.

Opcode 0x24 (36) - fillAtb

Summary

Fills the monster’s ATB bar, readying it for its turn.

Opcode	IfritAI name	Size	Short Description
0x24	fillAtb	1	Fills monster’s ATB bar

Parameters

None

Opcode 0x25 (37) - setScanText

Summary

Sets the extra scan text to a specific battle text.

Opcode	IfritAI name	Size	Short Description
0x25	setScanText	2	Sets extra scan text

Parameters

Position	Size	Name	Type	Short Description
1	1	TextID	int	The index of the text

Texts are defined in section 7 of c0mxxx.dat files.
Each text has an ID, starting from 0 and incrementing with each subsequent text.
TextID corresponds to this ID.

Opcode 0x26 (38) - statChange

Summary

Sets a multiplier that changes a selected stat.
The base stat does not get changed, so if for example we use statChange to change a stat to 500% of its original value, we just need to set the multiplier back to 100% to set it back to its base value.

Opcode	IfritAI name	Size	Short Description
0x26	statChange	3	Changes a stat

Parameters

Position	Size	Name	Type	Short Description
1	1	Stat	Stat	The stat that will be changed
2	1	Multiplier	int	The multiplier for said stat

Note that Multiplier is multiplied by 10, so for example if its set to 0x28 (40), the stat will be multiplied by 0x28 * 0x0A = 0x190 (40 * 10 = 400)

Opcode 0x29 (41) - draw

Summary

Makes previous ability draw magic from target (use after opcode useRandom or use).
This magic is stored, and if draw is used again, it will replace the previously stored magic.
In the case where draw is used on a playable character that has no magic or a monster, the message showing what magic was stolen will appear only the first time and a nameless magic with no effect that looks and sounds like Cure will be stored.
If a monster uses draw on itself and then uses cast, the game will crash.

Opcode	IfritAI name	Size	Short Description
0x29	draw	1	Draws magic

Parameters

None

Opcode 0x2A (42) - cast

Summary

Casts magic that’s been stored by using the draw opcode.
Using this after the monster used draw on itself will crash the game.
Note that if no magic has been stored, this opcode will do nothing.

Opcode	IfritAI name	Size	Short Description
0x2A	cast	1	Casts drawn magic

Parameters

None

Opcode 0x2E (46) - blowAway

Summary

Makes previous ability blow away magic from target (use after opcode useRandom or use).
Note that blown away magic is removed from junctions too.
Does nothing if the target has no magic.

Opcode	IfritAI name	Size	Short Description
0x2E	blowAway	1	Blow away magic

Parameters

None

Opcode 0x2F (47) - targetable

Summary

Sets this monster’s NOT Targetable flag to False.

Opcode	IfritAI name	Size	Short Description
0x2F	targetable	1	Makes monster targetable

Parameters

None

Opcode 0x30 (48) - untargetable

Summary

Sets this monster’s NOT Targetable flag to True.

Opcode	IfritAI name	Size	Short Description
0x30	untargetable	1	Makes monster untargetable

Parameters

None

Opcode 0x34 (52) - enable

Summary

Sets this monster’s Enabled flag to True.

Opcode	IfritAI name	Size	Short Description
0x30	untargetable	1	Enables monster

Parameters

Position	Size	Name	Type	Short Description
1	1	Target	int	Encounter slot of the monster

Target is the monster’s encounter slot, as defined in scene.out.