# Entropia Universe Armor Decay Formula

**Source:** "A Most Complete Guide to Armors (2020 Edition)"  
**Formula Author:** Hijacker27 (confirmed through testing)  
**Date:** 2026-02-09

---

## Armor Decay Formula (VU 15.15)

```
Decay (in PEC) = damage_absorbed * 0.05 * (1 - durability/100000)
```

Where:
- **damage_absorbed** = Amount of damage the armor piece absorbed
- **durability** = Armor's durability stat (varies by armor type)
- **Decay output is in PEC** (divide by 100 for PED)

---

## Armor Economy (hp/pec)

The economy can be calculated as:
```
hp/pec = 20 / (1 - durability/100000)
```

Or simplified:
```
hp/pec ≈ 20 + (durability/5000)
```

---

## Unlimited Armor Protection Costs

| Armor | Durability | hp/pec | dmg/100 PED decay |
|-------|------------|--------|-------------------|
| Ghost | 2000 | ~20.41 | 204,082 damage |
| Gremlin | 2950 | ~20.61 | 206,079 damage |
| Adjusted Nemesis | 3400 | ~20.70 | 207,039 damage |
| Angel | 4000 | ~20.83 | 208,333 damage |

**Analysis:** Using Angel instead of Ghost saves ~2 PED for every 100 PED of decay (2% savings).

---

## Limited (L) Armor Protection Costs

**Note:** Formula may differ for Limited armors with >10k durability (research ongoing).

| Armor | Durability | hp/pec | dmg/100 PED | vs Ghost |
|-------|------------|--------|-------------|----------|
| Martial (L) | 13,000 | ~22.99 | 229,885 | ⮟ 11.22% less decay |
| Mayhem (L) | 13,300 | ~23.07 | 230,680 | ⮟ 11.53% less decay |
| Angel (L) | 14,000 | ~23.26 | 232,558 | ⮟ 12.24% less decay |
| Perseus (L) | 15,000 | ~23.53 | 235,294 | ⮟ 13.27% less decay |
| Moonshine (L) | 15,400 | ~23.64 | 236,407 | ⮟ 13.67% less decay |

**Key Insight:** Limited armors with high durability (13k+) have significantly better economy than unlimited armors.

---

## Calculation Examples

### Example 1: Ghost Armor (2000 durability)
Monster hits for 15 Impact, armor absorbs all 15:
```
Decay = 15 * 0.05 * (1 - 2000/100000)
Decay = 15 * 0.05 * 0.98
Decay = 0.735 PEC
Decay = 0.00735 PED
```

### Example 2: Angel Armor (4000 durability)
Same 15 Impact hit:
```
Decay = 15 * 0.05 * (1 - 4000/100000)
Decay = 15 * 0.05 * 0.96
Decay = 0.72 PEC
Decay = 0.0072 PED
```

**Savings:** 0.015 PEC (2% less decay than Ghost)

### Example 3: Martial (L) (13000 durability)
Same 15 Impact hit:
```
Decay = 15 * 0.05 * (1 - 13000/100000)
Decay = 15 * 0.05 * 0.87
Decay = 0.6525 PEC
Decay = 0.006525 PED
```

**Savings:** 0.0825 PEC (11.22% less decay than Ghost)

---

## Implementation for Lemontropia Suite

### Python Implementation:
```python
from decimal import Decimal

def calculate_armor_decay(damage_absorbed: Decimal, durability: int) -> Decimal:
    """Calculate armor decay in PED.
    
    Args:
        damage_absorbed: Amount of damage absorbed by armor
        durability: Armor durability stat
        
    Returns:
        Decay cost in PED
    """
    durability_factor = Decimal(1) - Decimal(durability) / Decimal(100000)
    decay_pec = damage_absorbed * Decimal("0.05") * durability_factor
    return decay_pec / Decimal(100)  # Convert PEC to PED

# Example usage
decay = calculate_armor_decay(Decimal("15"), 2000)  # Ghost absorbing 15 dmg
print(f"Decay: {decay:.5f} PED")  # 0.00735 PED
```

### Armor Stats Database:
```python
ARMOR_DURABILITY = {
    "Ghost": 2000,
    "Gremlin": 2950,
    "Adjusted Nemesis": 3400,
    "Angel": 4000,
    "Martial (L)": 13000,
    "Mayhem (L)": 13300,
    "Angel (L)": 14000,
    "Perseus (L)": 15000,
    "Moonshine (L)": 15400,
}
```

---

## Plate Decay Formula

**Note:** Plate decay uses the same formula with plate's own durability.

```
Plate Decay = damage_absorbed_by_plate * 0.05 * (1 - plate_durability/100000)
```

**Important:** Plate and armor decay are calculated **independently** based on how much damage each absorbed.

---

## Research Notes

1. **Formula confirmed** by Hijacker27 and guide author through independent testing
2. **Limited armors >10k durability** may use different formula (needs more research)
3. **Decay is linear** per damage point absorbed (post-Loot 2.0)
4. **No minimum decay** - always proportional to damage absorbed

---

## References

- PlanetCalypsoForum: "A Most Complete Guide to Armors (2020 Edition)"
- Hijacker27's research on armor decay
- VU 15.15 patch notes (Loot 2.0 armor changes)