Lufia II's battle rules (Cellenseres's decompilation and vinheim3's disassembly, USA ROM)

Each enemy shown on a field map stands for an enemy group the map lists: when the map places an encounter actor, the game takes the actor's slot, reads the group in that slot of the map's encounter list, and sets up that slot's enemies from it. In the Ancient Cave the list is read from memory, where the cave writes it, rather than from the ROM. lufia-ii/field-encounter-slots

About: Lufia II: Rise of the Sinistrals Visible encounter

The slot routine is $81:8351 and the setup it calls $81:839F; the actor-setup call is at $80:ABA7. The ROM list at $97:B9AC is a table of word offsets by room, then each room's group numbers; Terror Wave names it MapFormationsObject. The cave's list is at $7F:F966.

Cited by: Random encounter, Visible encounter

How battles start on Lufia II's world map, and at what rate, isn't read yet. lufia-ii/world-map-encounters

About: Lufia II: Rise of the Sinistrals Random encounter

Cited by: Random encounter

Once an action isn't rejected by the target's status or interrupted, its damage is a base value scaled, given a random bonus, cut by half the target's defense, halved, and trimmed by a factor: X = base × scale / 16; X + X × v / 256, with v random from 0 to the action's variance − 1; less half the target's defense, at least 0; halved; then less X × F / 256, where F is the action's damage-factor byte. First a roll from 0 to 99 is made against the action's chance byte: below it, the action's own scale stands and the target's defense counts as 0, a heavier hit that ignores defense; otherwise the scale is 16, times 1. Healing takes the scale and the random bonus only. A scaled base past 65,535 runs into a $00 byte in the code rather than a result. The base, chance, scale, variance, defense, and factor come from the action's battle script, which isn't read here, and the lines read hold no miss test. lufia-ii/damage

About: Lufia II: Rise of the Sinistrals Damage formula

The routine is $85:D0CD; the damage steps run from $85:D20B to $85:D2C5, and the two $00 bytes are at $85:D243 (damage) and $85:D2AB (healing). The decompilation names the chance byte HIT_CHANCE and the counter at $7F:FAB7 ACTION_HIT_COUNTER. The random routine reads one of 55 bytes and refills them every 55 calls.

Cited by: Damage formula

Each defeated enemy can drop its item: the game needs a roll from 0 to 99 below the drop's chance, which is half the high byte of the stored drop word, and then a 1 on a roll from 0 to 3, so a chance of 40 drops on about 10% of kills. It rolls for each drop entry in the enemy's list, a later success replacing an earlier one, and stops rolling once the battle has won an item, so a battle pays at most one dropped item. lufia-ii/drop-roll

About: Lufia II: Rise of the Sinistrals Item drop table

The drop roll is $81:FB1A and the reward loader $81:FBDB. With the random bytes even, random(4) = 1 holds for 64 of 256 values, a quarter. The monsters table's drop column already gives the halved chance.

Cited by: Item drop table

Running from a battle has no roll in the code read: unless the battle's special-encounter flag is set, the party gets away at once. A battle loaded from the game's list of special encounters sets the flag, and there the attempt fails with a message and the battle goes on. When an enemy or the capsule monster runs, it alone leaves: it takes the status a defeated fighter gets, and the battle goes on. The routine's caller and the routines it calls aren't read, so a roll made there isn't ruled out. lufia-ii/run

About: Lufia II: Rise of the Sinistrals Fleeing

The run action is $81:AB94 (decompilation: battle_collective_actions.c). The world-map scene sets $11DD to 1 (world_scene.c, SaveEncounterView), which the same test would refuse; what clears it for an ordinary battle isn't read.

Taking a hit from an enemy fills a party member's IP gauge, more for a hit that takes a larger share of the HP the member had. The gain is m × g / 256 + 12, at most 255, where m = (256 − cos a) × 2, with a the hit's share of the member's HP in 256ths divided by 4 and rounded (64 is a right angle, so m runs from near 0 to 512), and g is the low byte of a word in the member's battle record times 128 / 100, at most 255 (199 instead when the word is $C800 or more). The gauge stops at 255. In the HP-change routine read, only an enemy's hit that leaves the member standing adds IP; a member who is knocked out drops to 0. lufia-ii/ip-gain

About: Lufia II: Rise of the Sinistrals Super meter

The IP byte is +$BC of the battle record (the decompilation's ACTOR_IP). The gain routine runs from $85:D529 to $85:D5D0; the divide is $85:DB6D and the cosine $85:DE1E. The gain is held to 255 before it is added, and the sum again. Which stat sits at +$33 isn't confirmed; the test of its high byte means a word from $0100 to $C7FF gives only its low byte. IP attacks cost up to 255 (lufia-ii-tables/ip-attacks). What the byte at +$BA counts isn't read.

The Ancient Cave has 99 floors, and the game builds each of the first 98 at random as the party reaches it; the 99th is a fixed map. Entering clears the floor count and arriving on the cave's map with a count of 0 sets it to 1; each floor is built with the count as its number and the count rises by one after it, and when the count stands at 99 the game loads the fixed map instead of building one. lufia-ii/cave-floors

The count is $7F:E696 (the disassembly's wAncientCaveFloorPlus1); the floor routine is $83:9E31, called from the field setup at $83:B26D. Map $F1 is the bottom floor. Archipelago's guide names its boss the Master Jelly; no code read here settles the boss. The entry routine sets the count to 0 ($84:87AA), so every visit starts at floor 1.

No Ancient Cave floor has a seed of its own. The builder draws on the random generator the rest of the game uses, after first spending between 1 and 32 of its numbers, one more than the frame counter's low five bits. That generator is a table of 55 bytes, stirred by XOR each time its numbers run out; it is seeded at power-on and again from a byte kept in the save whenever a save is loaded. lufia-ii/cave-seed

The generator is AequRNGval ($80:82C7); the disassembly calls it, or AequRNGtimesA beside it, from about 150 places, battle code among them, so every random event between saves moves the state a floor is built from. The routine at $80:914B that reseeds on load goes on to decode the save with the generator's numbers, and the save routine at $80:9184 stores a fresh random byte as the next key. The derandomizer's notes say the same in their words: the floor comes from the frame counter at $7E:0040 and the values at $7E:0520.

Each Ancient Cave floor is built rather than picked from stock maps. The builder lays out up to seven rectangular rooms, each one to four cells wide and one to four tall (the size the average of two draws), working left to right in bands down a grid 16 cells wide, and keeps a room only if it ends before column 9 and row 15 as the code counts; a room of a single cell is widened by one. Later passes, which the decompilation names for linking the floor, removing duplicate links, placing the start, the treasure room, the objects and chests, and drawing the cells, finish the floor. lufia-ii/cave-rooms

About: Lufia II: Rise of the Sinistrals Procedural dungeon

The grid is $7F:EA00, 256 bytes with rows $10 apart (a cell's index is row × 16 + column, $83:9CCB), so 16 by 16, as the decompilation says. The derandomizer's ac_subr.txt calls the same array 8x15, which matches the placement bounds (column + width < 9, row + height < 15), not the array. The placement keeps a room's cells in columns 1 to 7 and rows 3 to 13; the merge and linking passes after it fill cells beyond those bounds (the linking pass gives an empty cell beside a room that room's number, $83:9281 on), and lufia-ii/cave-layout-measured saw cells in columns 1 to 8 and rows 2 to 14. The random helpers are $83:9E1B (a byte times n, high byte) and $83:9DE4 (the mean of two).

Measured by calling the cartridge's own floor builder in Mesen 30 times for each floor from 1 to 98 (2,940 floors, the generator's state running on from one build to the next, from a state the probe sets rather than a save): every cell a floor used lay in columns 1 to 8 and rows 2 to 14 of the 16-by-16 grid, no floor had more than 7 rooms, 20 enemies, or 8 chests, and every enemy placed was one of the six its floor's entries in the enemy table allow. lufia-ii/cave-layout-measured

About: Lufia II: Rise of the Sinistrals Procedural dungeon

{
 "probe": {
  "builds": 2940,
  "columns": [
   1,
   8
  ],
  "rows": [
   2,
   14
  ],
  "rooms": 7,
  "enemies": 20,
  "chests": 8,
  "offTable": 0
 }
}

MesenCE 2.2.1 (build 4b8a196), Lufia II - Rise of the Sinistrals (USA). The probe calls the builder directly, so the floor routine's 1 to 32 discarded draws and the drawing passes don't run; the passes measured read only the floor count, the ROM's tables and the generator. The probe stops each build before the tiles are drawn. The rules measured are lufia-ii/cave-rooms and lufia-ii/cave-enemies, and the table lufia-ii-tables/cave-enemies.

Which enemies an Ancient Cave floor can hold depends only on its number: each enemy placed on floor N is entry 2(N − 1) plus a random 0 to 5 of a 200-entry table, so each floor has six kinds, a floor shares four of them with the next, and each entry serves three floors. A floor makes 4 to 7 tries to place an enemy, each at a random spot of a random cell, and a try fails when no cell is found or the spot is beside the start or another object; a treasure room adds up to 13 more, and a floor holds at most 20. lufia-ii/cave-enemies

About: Lufia II: Rise of the Sinistrals Visible encounter

The table is $94:D95C (file 0xA595C), the derandomizer's enemy table; Archipelago's options describe the vanilla game the same way, 'Ninja, e.g., is allowed to appear on the 3 floors B44-B46'. The objects placed here are the field enemies the encounter claim (lufia-ii/field-encounter-slots) reads back from $7F:F966.

Cited by: Level scaling, Visible encounter

An Ancient Cave floor has at most eight chests. The builder scans the grid for 2-by-2 blocks of cells in one room and tries a chest in each block, marking it used, until eight are placed or the grid scan ends; one floor in 16 can also get a treasure room, a 2-by-2 block that takes up to eight chest tries of its own and a cluster of up to 13 enemies. lufia-ii/cave-chest-places

Chests are $83:9ABC; it returns carry clear when it places a chest (inc $e734; clc) and carry set when the try is rejected, so the second counter the loop tests also counts placed chests and the chest count ends it first, as the decompilation's comment says. The treasure room is placed only where its 2-by-2 search finds a block. Which word a chest takes is in lufia-ii/cave-chest-contents.

Each Ancient Cave floor rolls the contents of its chests before it lays out its rooms: eight rolls of a byte from 0 to 255, one per chest. A roll of 174 or more gives a weapon, 129 to 173 a piece of armour, 99 to 128 a spell scroll for a spell none of the four party members knows (or else a restorative), 94 to 98 a blue chest, 36 to 93 a restorative, and 0 to 35 another consumable. Weapons, spells, blue chests and the other consumables are drawn evenly from their lists, and armour evenly from the first n mod 128 items of its list of n (lufia-ii/cave-armor-wrap); the restorative takes the average of two draws, so the middle of its list of nine comes up most. When an Iris treasure or Providence takes the first chest, the rolls fill the other seven. lufia-ii/cave-chest-contents

The shares are 82, 45, 30, 5, 58 and 36 in 256, as Archipelago's options list them. The derandomizer's help labels the 9-item table 'non-restorative' and the 31-item one 'restorative'; the ROM's lists are the other way round (Potion, Hi-Magic, Miracle in the nine; balls, boomerangs and gourds in the 31), which is how Archipelago describes them. The chest words are $7F:E746; an Iris or Providence word is written first by $83:90C5 (lufia-ii/cave-iris, lufia-ii/cave-providence).

Weapon and armour chests deepen with the floor: the builder lists, for each floor, every item marked as found in the field and not marked as excluded whose price is under (floor + 1) × 1,000 gold, or any price from floor 60 on, in item order; items of type 1 go on the weapon list and the rest on the armour list. lufia-ii/cave-item-pools

The derandomizer names the fields (bit 1 for inclusion, type 1 for weapons) and the price rule; the code agrees. Each list's end offset is kept as a word, but the chest pick reads only its low byte (lufia-ii/cave-armor-wrap).

From floor 10 on, Ancient Cave armour chests give only body armour. The chest pick halves the low byte of the list's length in bytes, so a list of more than 127 items is drawn from only its first n − 128: the armour list reaches 129 items at floor 10, where every armour chest holds its first item, an Apron, and from floor 60 it holds 185 and draws from the first 57, all body armour, which comes first in item order. Shields, helmets, rings and jewels come out of armour chests only on floors 1 to 9; the weapon list never passes 88 items and is drawn whole. lufia-ii/cave-armor-wrap

The end offsets are words ($5D for weapons from 0, $60 for armour from $1000), written 16 bits wide at $83:90A2-$83:90BA. A list of 128 items gives a count of 0, and random below 0 is 0, so that floor too gives only the list's first item. No source read here mentions the wrap. lufia-ii-tables/cave-item-pools gives each floor's listed and drawn counts.

Measured in the same 2,940 builds of floors 1 to 98 in Mesen (lufia-ii/cave-layout-measured): every armour roll gave an item from the first n − 128 of its floor's list once the list passed 127 items, and every one on floor 10 was an Apron; Providence first appeared on floor 21 and took the first chest of every floor-60-and-deeper build that no Iris treasure took; and with no new visit between builds, each of the nine Iris treasures appeared exactly once. lufia-ii/cave-chest-measured

{
 "probe": {
  "armorRolls": 3735,
  "outsideDrawn": 0,
  "floor10": [
   "Apron"
  ],
  "providenceFrom": 21,
  "everyBuildFrom60": true,
  "irisEach": 1
 }
}

MesenCE 2.2.1 (build 4b8a196). The Iris bits at $7F:E75E are cleared only on entering the cave, which the probe never does, so each treasure was offered once in the whole run; the event flags 200 to 208 were clear throughout. The rules measured are lufia-ii/cave-armor-wrap, lufia-ii/cave-providence and lufia-ii/cave-iris.

On each floor the Ancient Cave builds, there is a 5-in-256 chance that the game picks one of the nine Iris treasures at random for the floor's first chest. The treasure goes in only if it hasn't been picked before in this visit and the player hasn't already earned it: one bit per treasure, cleared on entry, marks it picked even when the chest isn't placed, and its event flag, set when the party leaves with it, marks it earned. No floor number is tested. lufia-ii/cave-iris

The flags are set by the exit (lufia-ii/cave-exit). TCRF's notes number flags 200 to 209 as treasures 1 to 10, with 202 also called the boss's flag; the code reads flags 200 to 208 for the nine items. Archipelago lists the nine Iris items (worlds/lufia2ac/Items.py#L455-L463).

From floor 21 on, an Ancient Cave floor's first chest can hold Providence (item $2D): the chance is about the floor number in 60, so certain from floor 60, unless an Iris treasure took the chest. Once a chest holding Providence has been opened, no more are placed in that visit. lufia-ii/cave-providence

Item $2D is named Providence in the ROM's name table. The official guidebook (p. 72, OCR) says the item is found from floor 20; the code's test is the floor count, which equals the floor's number during the build, against 21. Random below 60 is the high byte of a byte times 60, so floor n gives a chance of about n/60.

Entering the Ancient Cave takes everything from the party except its blue-chest items. The game moves each item on the blue list from the bag and from the four party members' equipment to a list of its own, saves a copy of the party, then clears all but the first 14 bytes of each of the seven members' records, the bag, the gold and the play time, puts 10 Potions in the bag, gives back the blue items, and rebuilds the seven members from their default records; when the byte at $0A7F, which neither source names, is 7, it also returns every capsule monster to level 1, a step no probe has covered. lufia-ii/cave-entry

About: Lufia II: Rise of the Sinistrals Metaprogression

The entry is $84:878A. The saved ranges are the seven member records ($0BAD, $532 bytes), the bag ($0A8D, $C0), the gold ($0A8A, 3), $119D-$11D7 (capsule monster state, by the decompilation's names), play time and counters ($0B4D, 5; $0B59, $F), $091E (8) and four blocks in bank $7F. The cleared ranges are the seven records from +$0E for $B0 bytes each, the bag, the gold, $091E, the play time and $0B59, and the $7F:F080 block. The blue test at $84:886D is misdecoded by the disassembly (and #$ff / ora / mvn); the decompilation reads it as and #$01FF, then the table compare. The guidebook (p. 72, OCR) says the party and capsule monsters go back to level 1 with 10 Potions; the level-1 records are the decompilation's reading of $81:ED35, not measured here.

Cited by: Metaprogression

When an Ancient Cave visit ends without a wipe, the party keeps its Iris treasures and its blue-list items and nothing else: the game collects every Iris treasure in the bag, setting its event flag, then every blue-list item in the bag or in any of the seven members' equipment, restores the copy of the party saved at the entrance, gives the collected items back, and adds the time spent inside to the restored play time. Iris treasures are collected from the bag only, and blue items brought in but no longer held are not returned. lufia-ii/cave-exit

About: Lufia II: Rise of the Sinistrals Metaprogression

The exit is $84:890B. The blue test at $84:8AF4 is misdecoded at $8AF6 (and #$ff / ora); the decompilation (src/cave/cave_exit.c#L8-L37) reads and #$01FF and an item of 0 skipped. The guidebook (p. 72-73, OCR) says the same in play terms: red-chest items stay in the cave, blue-chest items can be taken home and brought back in.

Cited by: Metaprogression

A party wipe in the Ancient Cave, a battle there or on its bottom floor that ends with every party member down, ends the visit with nothing gained. The game marks the visit lost, clears the party again without giving back its blue items, and counts the defeat; when the party then leaves, the exit skips the collecting, restores the copy saved at the entrance, and returns only the blue items the party brought in, so that visit's blue-chest finds and Iris treasures are lost. lufia-ii/cave-wipe

About: Lufia II: Rise of the Sinistrals Permadeath

The defeat routine is $84:8B9C. Its first bytes (A9 FF 8F 59 E7 7F, lda #$ff and sta $7FE759) are decoded by the disassembly as lda #$8fff.w and eor, so the decompilation is quoted for it. The guidebook (p. 72, OCR) says a wipe returns the party to the door at the exit. The code read here doesn't show the map change it makes; the routine sets map byte $05C0 to $F0.

Cited by: Metaprogression, Permadeath

Between visits the game keeps, outside the copy the exit restores, a count of entries and one of wipes, the total time spent in the cave, and the deepest floor reached; what else carries over is the Iris flags and the blue items as the party holds them. lufia-ii/cave-between-visits

About: Lufia II: Rise of the Sinistrals Metaprogression

The names of $0B68 to $0B72 are the decompilation's; the exit adds the hours and minutes and $0B5B into them ($84:8913-$84:894B). The deepest floor at $0B75 holds the count at the time of a build, the number of the floor being built; LiveSplit's Ancient Cave splits read it. Whether these bytes reach the save file is not read here.

Cited by: Metaprogression

The Ancient Cave changes its look and music in three bands of floors: floors 1 to 20, 21 to 40, and 41 to 98 each take their own block set, map header and music, chosen by (floor − 1) ÷ 10 from a 10-entry table; within a band the palette changes every two floors, through four. lufia-ii/cave-themes

Depth changes four things in the Ancient Cave and, in the code read here, nothing else: which six enemy kinds a floor can hold, the price ceiling of its weapon and armour chests, whether and how often Providence can appear, and the floor's look and music. The same count also picks the fixed bottom map at 99 and is kept as the deepest floor reached. The enemies keep the stats of their monster records; no routine that reads the floor number touches them. lufia-ii/cave-depth

The readers are the item lists ($83:9048, $83:9062), Providence ($83:9121, $83:912E), the enemy pick ($83:9A30), the floor routine ($83:9E31-$83:9F3A), the arrival ($83:B25D), the floor label ($80:C848) and a diagnostic display ($8E:B1C5). An indexed or indirect read would escape the search. The battle loader copies a monster's stats from its record with no floor term (lufia-ii-tables/monsters).

Cited by: Level scaling

Measured by running the cartridge's own entry, exit and defeat routines in Mesen on a party the probe stages rather than a save: Maxim alone at level 40, with Water spear equipped and Sizzle sword, five Potions and Mega ax in the bag (the three weapons are on the blue-chest list). Entry left Maxim at level 1 with nothing equipped and a bag of 10 Potions followed by the three weapons. After three more Potions and two blue-list weapons (Air whip in the bag, Blaze sword equipped) were added, the exit gave back level 40 and the five Potions, dropped the 13 cave Potions, and put all five blue-list weapons in the bag, the equipped ones included, with nothing equipped. After the defeat routine on a second visit, the bag held only 10 Potions, and the exit that followed gave back the bag from before the visit (Sizzle sword, five Potions, Mega ax) with Water spear, the weapon Maxim had equipped, added to it, and neither weapon found inside. The probe stops each exit at $84:8AE2, before the screen redraw. lufia-ii/cave-visit-measured

{
 "probe": {
  "home": {
   "bag": [
    "Sizzle sword",
    "Potion ×5",
    "Mega ax"
   ],
   "level": 40,
   "equipped": "Water spear"
  },
  "entered": {
   "bag": [
    "Potion ×10",
    "Sizzle sword",
    "Mega ax",
    "Water spear"
   ],
   "level": 1,
   "equipped": null
  },
  "inside": {
   "bag": [
    "Potion ×10",
    "Sizzle sword",
    "Mega ax",
    "Water spear",
    "Potion ×3",
    "Air whip"
   ],
   "level": 1,
   "equipped": "Blaze sword"
  },
  "left": {
   "bag": [
    "Sizzle sword",
    "Potion ×5",
    "Mega ax",
    "Water spear",
    "Air whip",
    "Blaze sword"
   ],
   "level": 40,
   "equipped": null
  },
  "defeated": {
   "bag": [
    "Potion ×10"
   ],
   "level": 1,
   "equipped": null
  },
  "wiped": {
   "bag": [
    "Sizzle sword",
    "Potion ×5",
    "Mega ax",
    "Water spear"
   ],
   "level": 40,
   "equipped": null
  }
 }
}

The weapons are the first five entries of the blue-chest list at $94:EEA0, read from the ROM by the probe; names from the item name table. The probe stops the exit at $84:8AE2, after its item and record work and before it redraws the screen, which a staged call can't finish. The probe doesn't reach the cave from a save, so what leads to the exit in play, the gold, and the other six members aren't measured. Level at record + $0E follows the decompilation's stat growth (GROWTH_RECORD_LEVEL_BYTE). The rules read in the code: lufia-ii/cave-entry, lufia-ii/cave-exit, lufia-ii/cave-wipe.