🎯 What Is Proc Coefficient?
Proc Coefficient is a multiplier that scales the effectiveness of triggering on-hit effects. When an item or weapon "procs" another item, the Proc Coefficient determines the actual chance of the triggered effect activating.
Proc Chance
Proc Coefficient
Chance Per Hit
Moldy Cheese has a 40% poison chance.
Holy Book has a Proc Coefficient of 0.5.
When Holy Book deals damage → actual poison chance = 40% × 0.5 = 20%
But if triggered by your weapon (Proc Coefficient 1.0) → actual chance =
40% × 1.0 = 40% (full chance)
⚡ The 8 Items That Can Proc Other Items
Only 8 items in Megabonk can trigger other items' effects when they deal damage. All other items can only be triggered by weapon attacks. These 8 items are split into two groups by their Proc Coefficient:
🟢 Proc Coefficient 1.0 (Full Chance)
These items trigger other items at full proc chance — identical to weapon attacks:
🟡 Proc Coefficient 0.5 (Half Chance)
These items trigger other items at half proc chance:
Items like Moldy Cheese, Lightning Orb, and Spicy Meatball cannot trigger other items. They can only be triggered by weapons or by the 8 items listed above. This is a common source of confusion — just because an item deals damage doesn't mean it can proc other items.
🎲 Common On-Hit Proc Items
These are the items that get triggered by weapon attacks and by the 8 proc items above. Their base proc chance is modified by the trigger source's Proc Coefficient:
| Item | Base Proc Chance | Effect | At 0.5 Coeff | Scaling |
|---|---|---|---|---|
Moldy Cheese
|
40% | Poison on hit | 20% | Linear |
Lightning Orb
|
25% | Lightning + stun | 12.5% | Hyperbolic (cap 90%) |
Spicy Meatball
|
25% | AoE explosion (65% dmg) | 12.5% | Fixed chance |
Dragonfire
|
15% | Fire + burn | 7.5% | Linear |
Bloody Cleaver
|
15% | Blood mark (bleed) | 7.5% | Linear |
Ice Cube
|
10% | Freeze on hit | 5% | Hyperbolic |
Notice the "Scaling" column: some proc items use linear scaling (additively stackable past 100%), while others use hyperbolic scaling (diminishing returns). The Proc Coefficient applies after the scaling calculation. Check each item's page in the Items Database for details.
⚔️ Weapon Proc Coefficients
Weapons also have Proc Coefficients. Most single-projectile weapons have a coefficient of 1.0,
but multi-hit weapons are balanced with lower values to prevent them from triggering procs too frequently.
| Category | Proc Coefficient | Examples | Note |
|---|---|---|---|
| Most Projectile Weapons | 1.0 | Shotgun, Revolver, etc. | Full proc chance per hit |
| Multi-hit / AoE Weapons | ~0.7 | Axe, Aura, Black Hole | Reduced to balance frequent hits |
The Black Hole weapon had its Proc Coefficient reduced from 0.9 to
0.7 in a patch update. This was because Black Hole hits many enemies continuously,
and at 0.9 it was triggering proc items (like Spicy Meatball) far too reliably, creating
overpowered chain reactions.
💡 The Overpowered Lamp
The Overpowered Lamp is a unique item that gives each on-hit proc one additional roll to trigger. It does NOT simply double the percentage — it adds an extra independent chance.
Without Lamp: Moldy Cheese has 40% chance → 40% to proc
With 1 Lamp: Two independent 40% rolls:
- Chance of at least 1 proc: 1 − (0.6 × 0.6) =
64% - Chance of 2 procs: 0.4 × 0.4 =
16%
The more proc sources you have, the better the Lamp scales. With many proc items, a single Overpowered Lamp dramatically increases overall proc consistency.
The Lamp is especially powerful with items that have moderate proc chances (25–40%). It also synergizes well with the 8 items that can proc other items — giving those proc chains an extra roll too. Combine with Moldy Cheese, Lightning Orb, and Spicy Meatball for maximum effect.
🧠 Build Tips for Proc Builds
1. Chain Proc Items for Maximum Value
Pair a high-coefficient proc item (Energy Core, Mirror, Cursed Doll = 1.0) with
powerful on-hit items like Moldy Cheese
or Lightning Orb. The 1.0 coefficient means those
items proc at full chance even when triggered by another item.
2. Use 0.5-Coefficient Items for Volume
Items like Cactus and Electric Plug hit frequently. Even at half proc chance, their high hit rate can generate more total procs than slower 1.0-coefficient items.
3. Match Proc Items with the Right Bracket
Remember that proc damage still goes through the damage bracket system. Proc item damage benefits from your damage multipliers — so optimizing your brackets amplifies your proc damage too.
4. Overpowered Lamp Is a Proc Build Keystone
If you're running 3+ proc items, the Overpowered Lamp is one of the highest-value pickups in the game. The extra roll on every single proc check multiplies your entire build's effectiveness.
❓ Frequently Asked Questions
What is Proc Coefficient in Megabonk?
Proc Coefficient is a multiplier that determines how effectively a weapon or item triggers proc-based effects. A coefficient of 1.0 means full proc chance; 0.5 means the proc chance is halved. Most single-projectile weapons have 1.0, but multi-hit weapons like Axe have ~0.7.
Which items can proc other items?
Only 8 items can proc other items: Energy Core, Mirror, and Cursed Doll (coefficient 1.0), plus Cactus, Electric Plug, Holy Book, Shattered Knowledge, and Toxic Barrel (coefficient 0.5). All other items can only be triggered by weapon attacks.
How does the Overpowered Lamp work?
The Lamp gives each on-hit proc one additional independent roll per lamp. A 40% chance becomes two 40% rolls, yielding 64% chance of at least one proc. It doesn't simply double the percentage — it adds an extra independent check.
Can proc items trigger themselves?
No. Even the 8 items that can proc other items cannot trigger themselves. A Holy Book cannot proc another Holy Book — only other on-hit items like Moldy Cheese or Lightning Orb.
Why do multi-hit weapons have lower coefficients?
Multi-hit weapons (Axe, Aura, Black Hole) hit many enemies per attack cycle. Without a reduced coefficient, they would trigger proc items far too many times, creating overpowered chain reactions. The ~0.7 coefficient balances their high hit rate against proc synergy.
📚 Explore More Mechanics
Understanding proc coefficients unlocks advanced build strategies. Continue learning with our other mechanics guides.