Drill to Earth's Core mutations are random modifiers on enemies. They start in the Stone Layer at 10 km, and most layers after it bring a new one. A mutated enemy is tougher or nastier, but most are worth more when you sell or burn the corpse. Below are all 8, from Fandom's Enemies and Layers pages and the patch notes.
All 8 Drill to Earth's Core Mutations
| Mutation | First layer | Effect | Sell price | Fuel |
|---|---|---|---|---|
| Stone | Crystal Layer | 0.75x speed. Only a pickaxe or explosives hurt it; it explodes when it dies and, since 22 August, drops an ore or gem. | Not listed | Not listed |
| Giant | Fossil Layer | Bigger and tankier, at 0.75x speed. | 1.5x | 3x |
| Void | Clay Layer | Tankier, and 25% faster since 29 August. | 1.5x | Not listed |
| Toxic | Toxic Layer | Its hit effect lasts 16 seconds. | 1.5x | Not listed |
| Frozen | Frozen Layer | Its hits slow you for 4 seconds: by 25% per Fandom's Enemies page, by 50% per its Layers page. | 1.5x | Not listed |
| Electric | The Abyss | 1.5x speed, and shocked enemies get a 50% speed boost since 29 August. | 1.5x | 2x |
| Fire | Glowing Core | Its hits set you on fire for 8 seconds, at 4% of your health per second. | 1.5x | 2x |
| Golden | Money Fog | Worth three times the coins. Money Fog and the Gunsmith's Level 3 make them. | 3x | Not listed |
"Not listed" means no source gives the multiplier. The Frozen slow is a conflict between two Fandom pages: 25% on the Enemies page, 50% on the Layers page.
How Mutation Effects Stack
Since the 3 October update, being hit again by the same mutation refreshes its timer instead of stacking it. The same update stretched Fire's burn from 6 to 8 seconds and Toxic's from 8 to 16. Past 100 km every regular enemy spawns with the Void and Fire mutations (Fandom's Enemies page), which is a big part of why Infinite Mode gets hard.
Stone Enemies and What They Drop
Stone enemies only take damage from a pickaxe or explosives, and they explode when they die. The 22 August notes add that the Black Hole Gun now deals explosive damage and can hurt them, and that Mounted Gunners spark against them to show their shots are not landing. Since 22 August a defeated Stone enemy drops one ore or gem:
| Size | Enemies | Odds |
|---|---|---|
| Small | Goblins, Spiders, Bat Minions, Crazy Miners, Bandit Miners | Coal 50%, iron 30%, gold 15%, diamond 4%, emerald 1% |
| Medium | Vampires, Goblin Knights | Iron 35%, gold 35%, diamond 20%, emerald 8%, ruby 2% |
| Large | Goblin Lords, Mole Men | Diamond 60%, emerald 35%, ruby 5% |
| Huge | Goblin Champions, Widows | Emerald 80%, ruby 20% |
Ore and gem prices are on the items page; the Demolitionist class is built around the explosives Stone enemies are weak to.
Golden Enemies
Golden is the only mutation not tied to a layer: Money Fog makes them, and so does the Gunsmith class's Level 3 perk. A Golden corpse sells for three times the coins.
Using Drill to Earth's Core Mutations to Your Advantage
- Burn Giant corpses for fuel: Fandom lists them at 3x fuel, and Electric and Fire corpses at 2x.
- The Goblin King class recruits goblins, and the 22 August notes say recruited mutated goblins pass their mutation's effect on to the enemies they hit (every mutation except Stone).
- Electric enemies move at 1.5x speed, and since 29 August shocked enemies get a 50% speed boost.
- Base stats for each enemy before mutations are on the enemies page, and the layers page lists the mutation each layer adds.
Drill to Earth's Core Mutations FAQ
Where do mutations start?
In the Stone Layer, at 10 km.
Which mutation is worth the most?
Golden: three times the coins. Most others sell for 1.5 times.
How do you kill Stone enemies?
With a pickaxe or explosives. Other weapons do not hurt them.
Do mutation effects stack?
No. Since 3 October a repeat hit refreshes the timer instead.