What slot does Green Nightmare Helm occupy in Mongil: Star Dive?

Green Nightmare Helm occupies the Hat slot. Each character can equip exactly one piece per slot, so swapping Green Nightmare Helm replaces whichever hat they had on.

What set does Green Nightmare Helm belong to?

Green Nightmare Helm is part of the Green Nightmare set — equip 2 pieces to unlock the first bonus and 4 pieces for the full set.

How do I reinforce Green Nightmare Helm?

Green Nightmare Helm reinforces up to level 15 using Enhancement Stones at the equipment forge. Reaching max level requires roughly 301,942 EXP and 905,826 gold.

Where does Green Nightmare Helm drop in Mongil?

Green Nightmare Helm drops from 3 stages listed in the "Where to farm" section above. Higher-difficulty stages drop the same piece at higher base stat rolls.

Is Green Nightmare Helm worth investing in?

SR pieces like Green Nightmare Helm hit the highest stat ceiling for the Hat slot. Reinforce one full set before spreading materials across alternates.

Mongil Codex · Hat · SR · Green Nightmare set

Green Nightmare Helm

4-star SR

A helmet that instills an uncanny fear in others. When you wear it, you'll project an overpowering presence.

Last updated May 2026 · Verified for the latest Mongil: Star Dive build

Last reviewed by Trakan — May 13, 2026

Green Nightmare set

Equip multiple pieces from the Green Nightmare set to unlock cumulative bonuses.

2-Set[2 Set] Ice DMG +3% for 2s upon using a Basic Attack
4-Set[4 Set] Crit DMG +3% for 5s upon using a Switch Skill on an enemy with Ice Affliction

Stats

Per-level stats — and the reinforcement cost to reach each level. Scrub the slider to see the cumulative EXP, gold, and best-fit Enhancement Stone mix update live.

LevelLv. 15/ 15

HP882+351 from Lv. 1

Reinforcement to Lv. 15

Target level: 15Lv.
Cumulative EXP: 226,461EXP
Cumulative gold: 905,826Gold

Recommended feed mix to reach Lv. 15

Substats — 1 slot

ATK213
DEF331
HP354
CRIT DMG1,550
CRIT Rate930
Fire DEF99
Ice DEF99
Wind DEF99
Lightning DEF99
Earth DEF99
Normal DEF99

Where to farm

Stages and bosses that drop Green Nightmare Helm, ranked by recommended difficulty.

Drop sourceView on map
Drop source
Drop source

Find Green Nightmare Helm on the interactive mapJump to the boss tile that drops this equipment piece.

Comments

Guides

In-house guides re-tested every patch.

Guides and articles content remains in English.

Mongil: Star Dive — Beginner Guide

Adventure map, jumping, gathering and the first-week checklist — every core mechanic the in-game tutorial walks you through, written in one place.

Trakan

Updated Patch 1.0

Reroll Guide — Best Targets and Stop Conditions

Best characters to chase on a fresh account, the fastest reroll path, and when the meta says you should stop and commit.

Trakan

Updated Patch 1.0

Best Team Comps — Destroyer, Slayer and Flex Slot

How team building actually works in Mongil — the Destroyer + Slayer + flex template the Stagger system rewards, when to break it for element-locked counters, and the Brawler-led sustained-DPS variant.

Trakan

Updated Patch 1.0

Combat Basics — Hold Attacks, Switch Skills, Ultimates

Basic attacks, special skills, switch skills and ultimate timing — the hold-input combat system explained without the in-game popup spam.

Trakan

Updated Patch 1.0

Frequently asked

What slot does Green Nightmare Helm occupy in Mongil: Star Dive?: Green Nightmare Helm occupies the Hat slot. Each character can equip exactly one piece per slot, so swapping Green Nightmare Helm replaces whichever hat they had on.
What set does Green Nightmare Helm belong to?: Green Nightmare Helm is part of the Green Nightmare set — equip 2 pieces to unlock the first bonus and 4 pieces for the full set.
How do I reinforce Green Nightmare Helm?: Green Nightmare Helm reinforces up to level 15 using Enhancement Stones at the equipment forge. Reaching max level requires roughly 301,942 EXP and 905,826 gold.
Where does Green Nightmare Helm drop in Mongil?: Green Nightmare Helm drops from 3 stages listed in the "Where to farm" section above. Higher-difficulty stages drop the same piece at higher base stat rolls.
Is Green Nightmare Helm worth investing in?: SR pieces like Green Nightmare Helm hit the highest stat ceiling for the Hat slot. Reinforce one full set before spreading materials across alternates.