This is information on mechanics and other random stuff that seemed useful for the HD-2D remake of Dragon Quest 3.

SIMPLIFIED ATTACK FORMULA

attack = math.min(850, attack)

baseDamage = attack * (1700 - attack) / 2000 * (1700 - defense) / 2000 * 0.7 * randrate

normalDamage = (attack - defense) * (1700 - math.max(attack, defense)) / 2000 * 0.6

damage = math.floor(baseDamage + normalDamage)

Any damage multipliers are added afterwards. "randrate" is your Luck modifier.

Physical damage can vary by 0.8x ~ 0.9x if below 0.9x Base Luck, 0.9x ~ 1.1x if between 0.9x and 1.1x Base Luck, and 1.1x ~ 1.2x if above 1.1x Base Luck (this is the "randrate" value). Attack also has a soft hard cap of 850, given the formula above.


CRITICAL HITS

Crit Damage substitutes the following for baseDamage:

attack * (2000 - attack) / 2000 * 0.7 * 1.2 

Then add to normalDamage as usual

Crit Chance = Luck / Luck Benchmark * Class Crit Multiplier

Crits are unaffected by Oomph / Egg On!


SIMPLIFIED SPELL DAMAGE FORMULA

Spell Damage = Spell Damage * Wisdom Modifier * Target Modifier * Each Modifier

Wisdom Modifier = 1 + Min( Max( Wisdom - Base Wisdom, 0) / 100, 0.6)

While spells can't crit, using a group/all-target spell on less than 4 enemies is a damage increase of up to +25% on a single target. For Target Modifier,

Using a group-target spell on 2 targets is 1.15x damage and 1 target 1.30x.

Using an all-target on 3 enemies is 1.1x, 2 enemies 1.2x, and 1 enemy 1.3x. Hero's Auroral Helm is 1.2x (Ka)Zap(ple) damage.


TURN ORDER

Turn order = (Agility + 20) * RAND(0.5 - 1.0)

Number is rolled each turn, highest values go first.


BASE STATS

Strength: added to weapon damage to calculate Attack

Resilience: added to equipment to calculate Defense

Stamina: calculates health: the maximum Hit Points at any time is between 195~205% of the character's Stamina score 

Agility: determines evasion and turn order. Turn order is calculated as ((Agility stat + buffs) + 20) * (N/100), with N being 50~100

Wisdom: calculates magic points and affects spell damage (see above). The maximum MP at any time is between 195~205% of the character's Wisdom score

Luck: affects resistance to status ailments, bonus chance of inflicting statuses, critical hit rate (see above), and physical damage. 

Avoiding status ailments 
The target's Luck is compared against the Luck benchmark: Luck / Luck Benchmark. The base chance for the status ailment to miss is then multiplied by the result, capped at 1.2 at the higher end and 0.8 at the lower end. 

Example: The enemy's spell has a 23% success rate,
If your luck is 20% or more greater than the baseline, then (100 - 23) x 1.2 = 92.4% avoidance.
If your luck is 20% or less than the baseline, then (100 - 23) x 0.8 = 61.6% avoidance. 

Bonus chance to inflict status ailments:
Base resistance - (0.25 * Luck / 1,000) = Adjusted enemy resistance


THIEF STEAL FORMULA

Theft = FLOOR?(Level/16 + 1) * item drop rate

Current theory is one enemy is randomly selected as the theft target at the beginning of each battle; the FLOOR component of the formula is not verified but likely.


WHERE TO FARM SEEDS

Seed of Life
016 Putrefido (Romario/Khoryv Region, Norvik Region)
041 Rottenweiler (Baharata Region, Near Alltrades Abbey, and Elsewhere)
051 King Squid (The Sea)
064 Ethereal Serpent (Tower of Transcendence, Mur Region, and Elsewhere)
087 Smackanape (Manoza Region, near the Pirates' Den, and Elsewhere)
105 Tentacular (The Sea of Alefgard)

Seed of Magic
048 Seaslime (The Sea)
072 Voodoogooder (Manoza Cave, Manoza Region, and Elsewhere)
133 Baramonster (???, Citadel Tower)

Seed of Strength
010 Healslime (Reeve Region, Asham Region, and Elsewhere)
030 Jackanape (Asham Region, and Elsewhere)
050 Merman (The Sea)
061 Ursa Minor (Near Alltrades Abbey, Jipang Region, and Elsewhere)
082 Rampage (Near the Wayfarer's Shrine, Lanson Region)
088 Ursa Major (Near the Shrine of the Dwarf, Manoza Region, and Elsewhere)
106 Infernal Serpent (Tantegel Region, Talontear Tunnel, and Elsewhere)
118 Skelegon (Damdara Region, Kol Region)

Seed of Defence
013 Killerpillar (Path of Promise, Romaria/Khoryv Region, and Elsewhere)
074 Shell Slime (Mur Region, and Elsewhere)
095 Wyrtoise (Maw of the Necrogond, Near Baramos's Lair, and Elsewhere)

Seed of Agility
003 Bunicorn (Aliahan Region, Reeve Region, and Elsewhere)
011 Spiked Hare (Reeven Region, Path of Promise, and Elsewhere)
023 Raven Lunatic (Norvik Region, Underground Lake, and Elsewhere)
060 Metal Slime (Near Alltrades Abbey, Tower of Transcendence, and Elsehwere)
084 Weaken Beakon (Near the Wayfarer's Shrine, Mur Region, and Elsewhere)
114 Ursa Mega (Craggy Cave, Kol Region, and Elsewhere)

Seed of Stamina
068 Belisha Beakon (Persistence Region, Near the Pirates' Den, and Elsewhere)
077 Cureslime (Edina Region, Near Baramos's Lair, and Elsewhere)
122 Green Dragon (Tower of Rubiss, Zoma's Citadel, and Elsewhere)

Seed of Wisdom
024 Bullmustiff (Norvik Region, Underground Lake, and Elsewhere)
033 Grillerpillar (Ibis Region, Near the Pyramid, and Elsewhere)
063 Beakon (Tower of Transcendence)
115 Umbra (Damdara Region, Tower of Rubiss, and Elsewhere)
120 Manticore (Tower of Rubiss)

Seed of Luck
009 Waspion (Dreamer's Town, Reeve Region, and Elsewhere)
026 Morphean Mushroom (Underground Lake, Portoga Region, and Elsewhere)
038 Lump Wizard (Portoga Region)
043 Hell Niño (Baharata Region)
079 Heedoo Voodoo (Theddon Region, Lanson Region, and Elsewhere)

Drop rates are unknown currently, AFAIK.
It's worth noting there's a good Slime Hill which features Seaslimes (Magic), Healslimes (Strength), Shell Slimes (Defence), Metal Slimes (Agility), Stamina (Cureslimes) and up to 8 Liquid Metal Slimes. North of Alefgard's Talontear Tunnel is two islands in the northwest ocean, the smaller one on the right with the Secret Spot is the aforementioned Slime Hill.


SPRITES

https://www.spriters-resource.com/pc_computer/dragonquestiiihd2dremake/