Ball Fusion Reference
The Fusion Reactor is the single most important drop in any run. It shows up randomly between waves and lets you combine your balls into something stronger. Knowing what to build before you see it is the difference between a run that clears VASTxVOID and one that dies in FUNGALxFOREST.
Fusion Reactor Basics
When you pick up a Fusion Reactor, it gives you one of three options depending on what you are carrying:
- Fission: Randomly upgrades the levels of your current balls or passives. If everything is already at Level 3, you get a gold payout instead.
- Fusion: Takes two unfused Level 3 balls and merges their properties into one ball. This frees up an inventory slot.
- Evolution: Takes two specific Level 3 balls (or passives) and creates a completely new, unique ball with abilities you cannot get any other way.
Evolutions are almost always the better choice. A fused ball mixes two movesets. An evolved ball gets a brand-new one that is usually stronger than either ingredient.
The endgame scaling trick: evolve your pairs first, then fuse the evolved balls together. Stacking two evolved movesets into a single ball is how you reach the damage numbers needed for NG+ runs.
Ball Evolutions
Every evolution listed here requires both ingredients at Level 3 before the Fusion Reactor will offer it.
| Evolution | Recipe | What It Does |
|---|---|---|
| Assassin | Iron + Ghost (or Dark) | Passes through the front of enemies but hits the back. Backstabs deal +30% damage. |
| Berserk | Charm + Burn (or Bleed) | 30% chance to make enemies go berserk for 6 seconds. Berserk enemies deal 15 to 24 DPS to anything near them. |
| Black Hole | Sun + Dark | Instantly kills the first non-boss enemy it hits, then destroys itself. 7-second cooldown between shots. |
| Blizzard | Freeze + Lightning (or Wind) | Freezes everything within 2 tiles for 0.8 seconds on impact. Deals 1 to 50 damage to caught enemies. |
| Bomb | Burn + Iron | Explodes on contact for 150 to 300 AoE damage. 3-second firing cooldown. |
| Erosion | Time + Wind | Infinite pierce. Shaves 3% to 5% of the target's max HP per hit. Ignores armor. |
| Flash | Light + Lightning | Deals 1 to 3 damage to every enemy on screen after impact. Blinds everything for 2 seconds. |
| Flicker | Light + Dark | Passively deals 1 to 7 damage to every enemy on screen every 1.4 seconds, regardless of where the ball is. |
| Freeze Ray | Freeze + Laser | Fires a straight freeze beam on impact. Deals 20 to 50 damage along the line with a 10% freeze chance. |
| Leech | Brood Mother + Bleed | Spawns parasitic baby balls that attach to enemies and stack bleeding damage over time. |
| Lightning Rod | Lightning + Iron | Creates a static point on hit that draws lightning arcs to it for concentrated chain damage. |
| Lovestruck | Charm + Light (or Lightning) | Charms multiple enemies at once, turning them into shields that block incoming projectiles for you. |
| Maggot | Brood Mother + Cell | Multiplies rapidly when it kills an enemy, flooding the screen with low-tier baby balls. |
| Magma | Burn + Earthquake | Heavy AoE kinetic damage combined with a lingering burn that keeps dealing damage after impact. |
| Mosquito King | Vampire + Brood Mother | Spawns aggressive tracking baby balls that heal you when they kill something. |
| Mosquito Swarm | Vampire + Egg Sac | Fires a cluster of small, fast healing projectiles that trigger when they bounce off the bottom of the screen. |
| Nosferatu | Vampire Lord + Mosquito King + Spider Queen | The ultimate vampiric ball. Requires three pre-evolved ingredients. Global lifesteal plus tracking swarm damage. |
| Noxious | Poison + Wind (or Dark + Wind) | Piercing projectile that leaves a toxic cloud along its path. High sustained damage. |
| Nuclear Bomb | Bomb (Burn + Iron) + Poison | Screen-clearing explosion with massive instant damage and lingering poison. The gold standard for wave clears. |
| Satan | Incubus + Succubus | High-tier demonic ball that rapidly drains enemy health across the entire screen. |
| Time Bomb | Time + Bomb | Sticks a delayed explosive charge to a target. Detonates for massive AoE damage after a short delay. |
| Timestop | Time + Freeze | Pauses all enemy movement and projectiles for 5 seconds (upgradable to 6). 30-second cooldown (reducible to 20). |
| Warp | Time + Light | Teleports to a random spot when it hits a target. Gains a 5% speed boost per warp, capping at 10%. |
Black Hole destroys itself after every kill and has a 7-second cooldown. It is a wave-clear tool, not a DPS ball. Do not rely on it as your only source of damage.
Passive Evolutions
Passives can also be evolved through the Fusion Reactor, but unlike balls, you cannot fuse passives together freely. Only specific pairs work.
| Passive Evolution | Recipe | What It Does |
|---|---|---|
| Arrow of Fate | Hand Mirror + Lover's Quiver | Blocks incoming enemy projectiles. When you get hit, it fires retaliatory baby balls at whoever shot you. |
| Cornucopia | War Horn + Baby Rattle | Massively increases the spawn rate and max count of your baby balls. |
| Deadeye's Impaler | Gracious Impaler + Deadeye's Cross (4 daggers) | Combines four directional daggers and a spear into an auto-targeting defensive array. |
| Grotesque Artillery | Turret + Hand Fan | Upgrades your turrets to fire wide-spread concussive blasts instead of single shots. |
| Odiferous Shell | Wretched Onion + Breastplate | Creates an aura around you. Any enemy that gets into melee range has a 50% chance of dying instantly. |
| Radiant Feather | Fleet Feet + (Light element) | Boosts projectile speed by 40% and your movement speed by 20%. |
| Soul Reaver | Everflowing Goblet + Vampiric Sword | Every enemy kill restores exactly 1 HP. Sounds small, but it adds up fast in swarm biomes. |
Post-Launch Additions
The ball pool has grown since launch. If you are missing any of these, check that your game is updated.
Regal Update (January 2026): Added 8 new special balls and 3 passive abilities.
Shadow Update (April 2026): Added 11 new special balls focused on time and spatial control, plus 4 new passive abilities. Notable additions include:
- Venom: Stacks slow debuffs per hit. Enough stacks trigger full paralysis.
- Time: Creates a localized freeze zone that locks down everything inside it.
- Reaper: Random chance to instantly kill non-boss enemies on hit.
- Sniper: Piercing kinetic shot that burns out when it hits a wall or reverses direction.
Quick Decision Guide
Not sure what to build? Here is how to think about it:
- Need wave clears? Go for Nuclear Bomb or Black Hole. Nuclear Bomb is better if you also have Maggot, since the mass kills flood the screen with baby balls.
- Need boss damage? Erosion is king. It shaves percentage HP, so it scales with boss health instead of against it.
- Need survivability? Mosquito King or Soul Reaver. Mosquito King gives better healing in dense waves. Soul Reaver is more consistent.
- Running a baby ball build? Cornucopia is mandatory. Pair it with Leech or Maggot for maximum screen coverage.
- Want to go AFK? Flicker deals passive damage without you doing anything. Pair it with Arrow of Fate for a build that plays itself.