Base Defense

How to Mob-Proof Your Base

A safe base is a math problem, not a fortress. Keep every surface at light level 8+cap your walls with a spider ledge, and seal the dark cave underneath. Do those three and zero hostiles spawn inside your perimeter.

LIGHT SCAN
 8+  SPAWN-SAFE
 1-7  RISKY
 0    MOBS SPAWN
Interior min: 12

15141260

OVERHANG LEDGE blocks spider climb

PERIMETERcaves sealed|slabs placed|roof lit0 HOSTILES

The 8-and-up rule

Hostile spawns are gated entirely on light level. 0 = mobs spawn, 1-7 = still risky8+ = fully spawn-safe. Light every floor, ceiling and ledge to that line and the only way a mob reaches you is by walking in from outside, which the slabbed-and-lit perimeter shuts down. Spiders are the exception since they climb and ignore light, so the overhang ledge does the work lighting can't.

What each mob can do to a wall, and from how far

Mob proofing works backwards from two numbers: how far a mob notices you, and how fast it closes. The speed column is the one people ignore. A slime moves at 0.6 and a vex at 0.7, both faster than a walking player, while a silverfish crawls at 0.25 and a zombie at 0.23.

Mob	Health	Hit damage	Movement speed	Follow range	XP
Phantom	20	2	0.7	16	5
Shulker	30	2	0.7	16	5
Ender Dragon	200	2	0.7	16	-
Vex	14	4	0.7	16	3
Breeze	30	3	0.63	24	10
Wither	300	2	0.6	40	50
Slime	16	4	0.6	16	query.last_hit_by_player ? query.variant : 0
Guardian	30	6	0.5	16	10
Evoker	24	2	0.5	12	10
Ravager	100	12	0.35	32	20
Vindicator	24	5	0.35	12	12
Piglin	16	5	0.35	16	5
Hoglin	40	6	0.3	16	5
Enderman	40	7	0.3	64	5
Spider	16	2	0.3	16	5
Creeper	20	2	0.25	16	5
Silverfish	8	1	0.25	16	5
Witch	26	2	0.25	16	12
Skeleton	20	2	0.25	16	5
Blaze	20	6	0.23	48	10
Zombie	20	3	0.23	35	5
Drowned	20	3	0.23	35	5

Quick answers

What light level stops mobs spawning?

Light level 8 or higher. At 7 or below, hostile mobs can still spawn on solid blocks; at 0 they spawn freely. Build to 12+ so you have margin and never drop under 8.

Do torches still work for spawn-proofing?

Yes. A torch emits light level 14 and stops spawns in roughly a 7-block radius before the light falls under 8. Lanterns and glowstone do the same and look cleaner; sea lanterns and glowstone are full-block and great for ceilings.

How do I stop spiders climbing my walls?

Spiders need a 2-wide gap to climb and they ignore light. Add a 1-block overhang ledge at the top of the wall, or finish the wall with iron bars / a fence lip. The outward lip means there is nothing above for the spider to grab, so the climb stops.

Why do mobs still appear inside a fully lit base?

Almost always a dark roof, an unlit cave underneath, or a single dark corner under stairs/overhangs. Press F3 in Java to read the block light level and hunt the dark spot. One unlit block can spawn a creeper.

Do I need to slab the whole area around my base?

Not the whole world. Cover or light a ring about 24 blocks out, the range mobs spawn from the player. Bottom slabs, carpet, or path lanterns all deny the spawn surface. Most players just light the perimeter instead.

What about phantoms and creepers specifically?

Phantoms spawn above you in open sky after 3 in-game days without sleep, so a roof plus regular sleep handles them. Creepers come from dark ground spawns, so the same light-to-8 rule kills the threat at the source.

Which hostile mobs are faster than me?

More than you would think. A big slime moves at 0.6 and a vex at 0.7, against a zombie's 0.23. Walking away works against most of the overworld and fails badly against those two.

What actually keeps mobs out?

Light, a roof and no path in. Height alone does nothing against a phantom, and a wall does nothing against a vex, which passes through blocks. Everything else is stopped by removing the route rather than the sight line.