Green Slime

HP 24
Gil 20 gil
Experience 84
Size Small
Damage 1
Attack Status Poison (Poison)
Hit Rate 1×84%
Critical Hit Chance 1%
Absorb 255
Evade 0%
Magic Defense 18%
Morale 124 (may run if party is level 22 or higher)
Elemental Vulnerability
Fire
Ice
Lightning
Earth
Status
Poison
Death
Encountered In
Marsh Cave
There are two creatures in the game with 255 Defense, and Green Slimes are the first you run into. They exist primarily to annoy you: they deal 1 damage per hit, but Poison their targets. A bunch of Green Slimes won't kill you, but it will drain your resources—both the Antidotes used to cure their Poison and the Spells used to actually kill them. 255 Defense means every attack will deal 1 damage per hit, unless it is a critical hit. Hoping for critical hits is no way to fight, so either hit these things with Fire (or Ice) Spells, or simply run away.

As an aside, D&D veterans may recognize Green Slime as more of an obstacle than an actual creature, which explains some of their statistics—not to mention their high surprise factor.
Compare Green Slime to other Monsters
Random Encounters: With Green Slime – 6 shown
Map
The monsters that can be involved in this encounter; minibosses are only found in repeatable set encounters; bosses are encountered only one time during the game; the final boss must be defeated to complete the game; superbosses are the most dangerous monsters in the game
Monsters
The probability of any given encounter being this one when you have a random battle on its map
Frequency
A modifier to the base chance of the monsters surprising the party; your party leader's agility and luck also factor into the surprise chance
Surprise
Is it possible to run from this encounter?
Run?
The average amount of total experience you can expect to earn from this encounter (this is split evenly among surviving party members)
Avg. Exp.
The average amount of gil you can expect to earn from this encounter
Avg. Gil
Marsh Cave B1 Green Slime ×2–4 18.8% +51% Yes 252 60 gil
Marsh Cave B2 Green Slime ×2–4 18.8% +51% Yes 252 60 gil
Marsh Cave B3 Green Slime ×2–4 18.8% +51% Yes 252 60 gil
Marsh Cave B1 Tarantula ×1–2, Black Widow ×0–2, Gray Ooze ×0–1, Green Slime ×0–1 9.4% +51% Yes 411 128 gil
Marsh Cave B2 Tarantula ×1–2, Black Widow ×0–2, Gray Ooze ×0–1, Green Slime ×0–1 9.4% +51% Yes 411 128 gil
Marsh Cave B3 Tarantula ×1–2, Black Widow ×0–2, Gray Ooze ×0–1, Green Slime ×0–1 9.4% +51% Yes 411 128 gil
Shadow Crawler

Related

Gray Ooze

HP 76
Gil 70 gil
Experience 255
Size Small
Damage 30
Hit Rate 1×93%
Critical Hit Chance 1%
Absorb 7
Evade 2%
Magic Defense 28%
Morale 152 (may run if party is level 36 or higher)
Elemental Vulnerability
Fire
Ice
Lightning
Earth
Status
Poison
Death
Encountered In
Marsh Cave
Mt. Gulg
After seeing the 255-Defense Green Slimes, you might assume that Gray Oozes are also immune to physical attacks, but this is not the case. In point of fact, Gray Oozes have very low defense, and can be taken down in one or two powerful attacks. And they should be, because they have a powerful attack of their own.

Ochre Jelly

HP 76
Gil 70 gil
Experience 252
Size Small
Damage 32
Hit Rate 1×93%
Critical Hit Chance 1%
Absorb 6
Evade 3%
Magic Defense 28%
Morale 144 (may run if party is level 32 or higher)
Elemental Vulnerability
Fire
Ice
Lightning
Earth
Status
Poison
Death
Encountered In
Terra Cavern
Ochre Jellies deal a lot of damage, but they are more notorious for being difficult to find than being difficult to fight. The best place to look if you're rounding out your bestiary is the bottom floor of the Terra Cavern. Watch out of their powerful attack. Fortunately their defenses are pathetic, and it shouldn't take more than one or two attacks to take one out.

Dark Flan

HP 156
Gil 900 gil
Experience 1,101
Size Small
Damage 49
Attack Status Poison (Poison)
Hit Rate 1×103%
Critical Hit Chance 1%
Absorb 255
Evade 12%
Magic Defense 43%
Morale 200
Elemental Vulnerability
Fire
Ice
Lightning
Earth
Status
Poison
Death
Encountered In
Flying Fortress
Temple of Chaos Past
Dark Flans are a throwback to the Green Slimes you met in the Marsh Cave, in that they are virtually immune to physical attacks. You can break through their Defense with critical hits, which should be quite common at this stage of the game, but in the groups they appear in are too large for this to be efficient (though their attacks aren't terribly powerful so it may be an option). Hit them with Fire3 or, if you want to save Spells, see how many you can take out with the Venom Blade. Flare is also highly effective if you can spare the Spell slot.

SCUM

Sprite
HP 24
Gold 20 G
Experience 84
Absorb 255 Evade 0% Magic Def. 18%
Damage 1–2 Hit 84%
Attack Status Poison (Fire, Cold)
Critical Hit Chance 1%
Morale 124 (may run at party level 22+)
Elemental Vulnerability
Fire
Cold
Lightning
Earth
Status
Poison
Death
Encountered In
Marsh Cave
SCUMS have a weak attack that causes Poison, and usually gain surprise. They also have 255 Absorb, meaning anything but a critical hit will deal 1 damage to them. FIR2 will take out a full group, while FIRE or ICE will take out a single SCUM. In truth, SCUMS are more of an obstacle than an enemy. They are not worth wasting valuable Spells on—you're better off simply running away.

Green Slime

Sprite
Rank 2
HP 10
MP 6
Average Drop Value
8 gil
Power 4 Attacks 1×50% (0.5)
Attack Effect Venom
Defense 210 Evasion 0×0% (0.0)
Magic Resistance 1×50% (0.5)
Monster Family Earth, Magic Beast
Fear −20% (50% at 2,250 party HP)
Treasures 3 gil (40%), 6 gil (30%), 12 gil (20%), 25 gil (10%)
Elemental Vulnerability
Fire
Poison
Ice
Matter
Mind
Death
Body
Encountered In
Semitt Falls
Slimes are annoying creatures that are nearly impossible to destroy physically. Hit the group with Blizzard or Fire to take it out. If you lack the proper Spells, it's best to just run away.