L2 Hostility

There is a level associated with all enemies. Level is determined by the dimension, biome, position, nearby player difficulty, and entity type. As the level becomes higher, mobs have higher health and deal higher damage, and higher chance to have strong traits.

There is a difficulty level assigned to chunk sections and players. Killing mobs to gain chunk and player difficulty, and die to lose player difficulty. Use Hostility Detector to know about current difficulty, use Hostility Orb to make a chunk section permanently not spawning mobs with level.

Regular Traits

• Fiery: Mobs can ignite you when attacked or attack you.
• Invisible: Mobs and their armors/weapons will become invisible. Use Detector Glass to see them.
• Protection: Mobs get damage resistance effect
• Regenerate: Mobs will regenerate health slowly.
• Speedy: Mobs will move at absurd speed
• Tank: Mobs will gain much more health and armor
• Shulker: Shoot shulker bullets every few seconds. It will not inflict levitation, but will inflict other potion effects the mob carries.
• Gravity: mobs and players around it will have higher gravity, falling faster and jumping lower
• Moonwalk: mobs and players around it will have lower gravity, falling slower and jumping higher
• Counter Strike: when the mob is attacked, after it lands on ground, it will attempt to dash-strike back, launching itself toward target.

Advanced Traits

These traits only appear after Lv.100

• Adaptive: Mobs will get memorize and get used to damage types. Higher level allows mobs to memorize more damage types
• Reflect: Mobs will reflect direct physical damage. Try to use arrow or magic.
• Grenade: Shoot explosive bullet every few seconds after the previous bullet disappears.
• Growth: Slime only. Slime will grow larger when healed to full health. Growth III slime can be very large.
• Split: Mobs will split into 2 with half level and same trait (with 1 level lower split trait) when killed. Subsequent mobs won't drop anything.
• Drain: Mobs will remove random positive potion effects, and increase duration of negative effects on target. Deals more damage if target has negative effects.
• Reprint: When hit target, copy target equipment enchantments. Increase damage based on target total enchantment points
• Corrosion: Appears only after Lv.200. When mob hit target, it will consume target equipment durability based on lost durability. Use Hardened enchantment to mitigate this effect.
• Erosion: Appears only after Lv.200. When mob hit target, it will consume target equipment durability based on remaining durability. Use Hardened enchantment to mitigate this effect.

Potion Traits

• Blinder - Blindness
• Distorter - Nausea
• Levitater - Levitation
• Stray - Slowness
• Weakener - Weakness
• Poisonous - Poison
• Withering - Wither
• Cursed (from L2Complements)
• Soul Burner (from L2Complements)
• Freezing (From L2Complements)

Legendary Traits

These traits will only be unlocked when you kills a mob with Rank 5 traits, and appear only after Lv.100

• Dementor: Mobs will be immune to physical attack, and their damage will bypass armor
• Dispelling: Mobs will be immune to magic attack, and their damage will bypass magical protections. They can also disable enchantments on your equipments for a short time
• Teleport: Mobs can teleport to avoid physical damage. Try to use magic.
• Repelling: Mobs will repel you. Use full set insulation enchantment to reduce the force.
• Pulling: Mobs will pull you toward it. Use full set insulation enchantment to reduce the force.
• Undying: Mobs will respawn indefinitely. Try to use Cursed potion or weapons that can inflict Cursed effect
• Killer Aura: Appears only after Lv.300. Mobs will deal damage to nearby targets every few seconds, range indicated by particle effects.
• Ragnarok: Appears only after Lv.600. When mob hit target, mob will "seal" some equipments or curios on target, which can be unsealed by hold using the item for a few seconds.

Twilight Forest:

• Naga will have at least Lv.50
• All mini bosses will have at least Lv.100
• All other bosses will have at least Lv.150
• All bosses will have Cursed trait and 1 other fixed trait
• All boss spawners can be crafted with respective trophies, trait symbols of the traits they have as fixed traits, and chaos ingot.

Ice and Fire: 

• All dragons are spawned with at least Lv.100 and 3 fixed traits including Regen and Adaptive. Don't attempt to fight them before you know how to deal with high level Regen and Adaptive. Though they will never gain Tanky trait as they are already tanky enough.
• Ghosts will carry Dementor trait at higher level, making them immune to all damage except magic damage.
• Siren will carry Drain and Distorter trait at higher level.

Cataclysm:

• All minibosses will have at least Lv.100 and 2 fixed trait
• All bosses will have at least Lv.200 and 3 fixed trait
• When bosses are higher than Lv.600, they carry special curios items making them extremely threatening.
• (starting from 2.4.24) Ignis and Ancient Remnant will spawn minions to help them. At Lv.400 or higher, they will also spawn relevants that protect them from damage.

Bosses of Mass Destruction:

• All bosses will have at least Lv.200 and 3 fixed trait

Mutant Monsters: (starting from 2.4.22)

• All mutant monsters will not spawn naturally unless they are at least Lv.100
• After Lv.150, all mutant monsters have 50% chance to gain Reprint
• After Lv.200, all mutant monsters have 50% chance to gain Adaptive

Gateways to Eternity (starting from 2.4.23, datapack based)

• Growth gateway: Spawns high level slime and magma cube with growth trait, dropping 2 growth trait symbols
• Split gateway: Spawns high level zombies, skeletons, and respective variants with split trait, dropping 2 split trait symbols

Mowzie's Mobs (starting from 2.4.24)

• Bosses will be at least Lv.100