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Scrap Mechanic Raid Defense — How Raids Work & How to Survive Them

How Scrap Mechanic raids work: trigger math, raid levels, defense builds, turrets, water cannons and the level 5 raid achievement.

Last Updated: 2026-08-12

Scrap Mechanic Raid Defense — How Raids Work & How to Survive Them

Raids are Scrap Mechanic's consequence engine: the bigger your farm, the harder the game pushes back. Understanding the trigger math and building real defenses separates a sustainable base from a pile of lootable ruins. This guide explains how raids scale, the defense builds that survive them, and how to hit the "Master of defence" (level 5 raid) achievement.

Scrap Mechanic raid defense
Scrap Mechanic raid defense

How Raids Work

  • Raids trigger from crops — plant 8 or fewer tier-1 crops per chunk and raids won't start; each chunk of farmland above that raises raid intensity
  • Raid level scales with farm size and tier — more crops, higher-tier crops and larger farm chunks push the raid level up
  • Raids target your base and farm — bots path in, attack structures, and steal/destroy if unopposed
  • Bots vary by raid — Farmbots are the baseline; higher raids mix Haybots, Totebots and Minerbots (see Bots & Enemies)

Community tools like the raid calculator estimate the raid level your current farm layout will pull — worth running before you expand.

Defense Principles

  1. Don't farm in the base — separate the farm chunk from the living base; raids hit the farm, not your bed
  2. One funnel, one kill zone — bots path through gaps; build an "open" wall with a single gap and stack firepower on it
  3. Bait plants — keep a small crop patch near the gap so bots commit to the funnel instead of pathing around
  4. Elevation — bots struggle with stairs and vertical walls; a raised kill box with a stair gap is the classic design
Walls delay, turrets kill

A wall without weapons just postpones the raid — bots chew through walls. Pair every wall section with firepower (turret, spud gun emplacement or water cannon).

The Auto-Defense Build

The community standard auto-turret farm defense:

  • Turret seats (gunner positions) on armored mounts
  • Sensors at the funnel gap wired to logic gates (AND: sensor + manual switch) — so turrets fire automatically or on your command
  • Spud guns with ammo chests — the ammo economy is your farm, so defense feeds itself
  • Water cannons as crowd control — they knock bots back without killing them (and earn the "Wet circuits" achievement for soaking a Haybot)

Logic wiring details are in the logic gates guide.

The Level 5 Raid & "Master of defence"

The "Master of defence" achievement requires successfully defending against a level 5 raid. Practical route:

  • Expand the farm deliberately to push raid level to 5
  • Full auto-defense (turrets + water cannons + funnel) in place before you trigger it
  • Keep the farm off-site from the living base
  • Stock ammo — a level 5 raid is a sustained fight

This is the hardest of the raid achievements; pair it with the achievements guide 100% route.

FAQ

How many crops trigger a raid? Community-verified: 8 or fewer tier-1 crops per chunk means no raids; the threshold drops as crop tier rises.

Can I disable raids? In Creative Mode, yes (no raids at all). In Survival, no — but keeping the farm small avoids them entirely.

What's the best raid defense? The funnel + auto-turret + water cannon combo. Details above.

Do raids scale with players? Raid intensity tracks farm size primarily; co-op groups face the same raids as solo with the same farm.

Official resources: Steam store page · Official Scrap Mechanic Wiki — Survival Mode · Steam Community — Raid Discussion · Wikipedia · IGN game page

Last Updated: August 12, 2026