Ball Fusion Reference
The Fusion Reactor is an item sometimes dropped by enemies mid-run, and it offers one of three choices: Fission, Fusion, or Evolution. Evolution is almost always the right pick, because it creates a brand-new ball stronger than either ingredient. Both ingredients must already be at Level 3 before an evolution is offered.
The Fusion Reactor is the single most important drop in any run. Enemies sometimes drop it as you fight, and it 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 (or Sun + Time) | Instantly kills the first non-boss enemy it hits, then destroys itself. 7-second cooldown at Level 1, dropping to 6 and then 5 as it levels. |
| 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% of the target's current health per hit, so it bites hardest against full-health bosses. |
| 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, or Time) | 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 | Detonates for 300 to 500 damage to nearby enemies and applies radiation stacks (up to 5, each raising damage taken by 10%). 3-second cooldown. The gold standard for clearing packs. |
| 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 on a 30-second cooldown, then destroys itself after hitting an enemy. |
| 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. |
| Wings of the Anointed | Radiant Feather + Fleet Feet | The movement-and-launch-speed evolution. Radiant Feather itself is a base passive (+20% launch speed with slight knockback), not an evolution. |
| Soul Reaver | Everflowing Goblet + Vampiric Sword | Every enemy kill restores 1 HP and can overheal you by up to 30%. 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 (Freeze + Poison): Stacks slow debuffs per hit. A full stack buildup triggers paralysis.
- Time: A new base ball that creates a localized time snare, locking down everything inside it.
- Reaper (Soul Sucker + Heart Swallower): 10% chance to kill on impact, healing you for 5 when it does.
- Sniper (Shuriken + Shotgun): Pierces enemies and releases 3 to 7 sniper baby balls when it hits a wall. The baby balls are what walls destroy.
Naturalist Update (August 6, 2026): the third and final free update. It adds 11 new balls and 5 new passives, listed below, plus 2 characters covered in Characters.
Which balls did the Naturalist Update add?
The update adds 11 balls. Flesh is the only new base ball, and the other ten are evolutions with the recipes below.
| Ball | Recipe | What It Does |
|---|---|---|
| Lightning Bug | Brood Mother + Lightning | Spawns a firefly on every bounce. Each firefly seeks out the strongest enemy, then zaps nearby targets with a burst of lightning. |
| Mosquito Kingdom | Mosquito King + Mosquito Swarm | Spawns one or two mosquitoes whenever it hits an enemy, building a swarm over time. The mosquitoes hunt the weakest target on the field for 100 to 150 damage per attack, and a killing blow returns a small amount of health to you. |
| Drill | Earthquake + Iron | Pierces straight through enemies from behind, dealing extra damage along the way. |
| Flesh | Base ball | Starts at half damage, then gains speed with every bounce until it is crossing the screen as a blur. |
| Armageddon | Inferno + Storm | Marks the first enemy it hits, then calls down a meteor shower that deals heavy damage to everything within a three-tile radius. |
| Offspring | Cell + Flesh | Not yet documented. |
| Petrify | Stone + Flesh | Not yet documented. |
| Tumor | Radiation Beam + Flesh | Not yet documented. |
| Zombie | Vampire + Flesh | Not yet documented. |
| Flesh Mound | Brood Mother + Flesh | Not yet documented. |
| Elemental | Earthquake + Burn + Freeze + Wind | Not yet documented. |
Which passives did the Naturalist Update add?
The update adds five passives. Platinum Dumbbell is the only new base passive, and the other four are evolutions with the recipes below.
| Passive | Recipe | What It Does |
|---|---|---|
| Platinum Dumbbell | Base passive | Gives your balls a damage boost that holds until they collide with the back wall. |
| Inglorious Hammer | Platinum Dumbbell + Upturned Hatchet | Balls that hit a wall or the back of the arena immediately strike a random enemy for reduced damage. |
| Remote Detonator | Magnet + Pressure Valve | Spawns a level 1 Bomb Ball every time an enemy dies. |
| Ardent Tire | Rubber Headband + Wagon Wheel | Not yet documented. |
| Windweaver | Bottled Tornado + Slingshot | Not yet documented. |
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 a percentage of current health per hit, so it stays relevant no matter how big the health pool gets.
- 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.
Frequently Asked Questions
What are the three Fusion Reactor options in Ball x Pit?
Fission randomly upgrades the levels of your current balls or passives, and pays out gold instead if everything already sits at Level 3. Fusion merges two unfused Level 3 balls into one and frees an inventory slot. Evolution combines two specific Level 3 balls or passives into a new ball you cannot get any other way.
Should you fuse or evolve in Ball x Pit?
Evolve. A fused ball only mixes two existing movesets, while an evolved ball gets a brand-new one that is usually stronger than either ingredient. For NG+ scaling, evolve your pairs first and then fuse the evolved balls together.
What is the best ball for boss damage?
Erosion, made from Time plus Wind. It has infinite pierce and shaves 3% of the target's current health per hit, so it stays relevant against every health pool in the game.
How does Nuclear Bomb work in Ball x Pit?
Nuclear Bomb evolves from Bomb, itself made of Burn plus Iron, combined with Poison. It detonates for 300 to 500 damage to nearby enemies on a 3-second cooldown and applies up to 5 radiation stacks that each raise damage taken by 10%. Pair it with Maggot, because the mass kills flood the screen with baby balls.
What have the post-launch updates added to the ball pool?
The Regal Update in January 2026 added 8 new special balls and 3 passive abilities. The Shadow Update in April 2026 added 11 more special balls focused on time and spatial control plus 4 new passives, including Venom, Time, Reaper, and Sniper. The Naturalist Update on August 6, 2026, the third and final free update, added 11 more balls and 5 more passives, among them Armageddon, Lightning Bug, and the Remote Detonator passive that spawns a level 1 Bomb Ball on every kill.
What to Read Next
- Fast-Clear Builds. Builds these fusions are meant to reach.
- Characters. Attributes that favor specific ball lines.
- New Ballbylon. The economy funding your fusion attempts.
- Tips and Tricks. Fission versus fusion versus evolution, and why you evolve first.