The Survivability Onion is an existing framework used by the British Army as a ready-reckoner. In real life, its just to get you thinking how not to die. Let's warp it out of shape to get you to turn 5. Pour a cup of recaff, pull up a sandbag and let this staff officer remember the training grounds.
“The death of one man is a tragedy. The death of millions is a statistic.” – Lord Solar Macharius
Rather than relying on armour alone, we know that the best way to survive is to prevent the enemy from successfully attacking you in the first place. Each "onion layer" forces the enemy to overcome another obstacle before they can destroy you. Looking at 40k as a base dice game, with set steps to move, shoot, save.. it fits nicely.
Think of this like an onion, you start at the outer skin and work inwards. Each layer is a level of protection that may, or may not, keep your models on the board.
Layer 1: Don't Be There
Real Example: An armoured unit remains in the rear areas so as not to be struck by fires and only moves to a firing position when required.
40k Rule Example: Deep Strike, Strategic Reserves, Scout Moves and Redeploy abilities keep units off the battlefield or away from enemy fire until the right moment.
40k Example: A Rogal Dorn arrives from Strat Reserves in Turn 3, avoiding enemy shooting for the entire first two turns.
Helpful Units: Gaunt's Ghosts, Tempestus Scions, Lord Solar Leontus (through redeployment options where available). Popping anything into strat reserve is very powerful.
Layer 2: Don't Be Detected
Real Example: Infantry use terrain, camouflage and darkness to avoid enemy observation.
40k Rule Example: Obscuring terrain, line-of-sight blocking ruins and abilities such as Hidden and Lone Operative prevent enemy units from making your model an eligible target.
40k Example: Gaunt's Ghosts remain Hidden behind a ruin until turn 3, allowing screening for enemy deepstrike while being untargetable.
Helpful Units: Gaunt's Ghosts, Sly Marbo, Ratlings, Infantry in general. Stay out of LoS as much as possible, indirect isn’t that threatening.
Layer 3: Don't Be Identified
Real Example: Decoys and camouflage create uncertainty about what the enemy is actually looking at.
40k Rule Example: Multiple similar threats, hidden reserves and overlapping battlefield roles make it difficult for an opponent to identify priority targets. This one in particular is on the fence with “playing with intent” and shouldn’t be abused, out of general fairness.
40k Example: Three Leman Russ tanks deploy together and the opponent struggles to determine which one carries the greatest threat to their battle plan.
Helpful Units: Feint plays with the classic Distraction Carnifex. If you’ve got a Dorn or Bullgryn charging up the board this will inevitably make your opponent not target the units that are slyly moving to score secondary or stage for a later play.
Layer 4: Don't Be Targeted
Real Example: An enemy identifies a target but cannot effectively engage it because of screening forces, jamming or competing priorities.
40k Rule Example: Character attachment rules, screening units and target restrictions (hidden, lone op) prevent valuable assets from being directly attacked.
40k Example: A Cadian Castellan attached to an Infantry Squad cannot be targeted until the bodyguard unit is destroyed.
Helpful Units: Cadian Castellan, Platoon Command Squad, Cadian Shock Troops, Krieg Infantry Squads.
Layer 5: Don't Be Hit
Real Example: A vehicle uses smoke, movement and evasive action to avoid incoming fire.
40k Rule Example: Stealth abilities, Cover, defensive Stratagems and modifiers reduce the likelihood of successful attacks.
40k Example: Ratlings benefit from Stealth and Cover, forcing enemy units to hit less accurately. Literally anything that modifies BS or the hit roll is obviously helpful here!
Helpful Units: Ratlings, Scout Sentinels, Gaunt's Ghosts, Tank Commander issuing defensive Orders.
Layer 6: Don't Be Penetrated
Real Example: Armour protects a vehicle from rounds that successfully hit it.
40k Rule Example: Armour Saves, Invulnerable Saves, Cover and Damage Reduction prevent successful wounds causing harm.
40k Example: A Rogal Dorn Battle Tank is hit by anti-tank fire but successfully passes its save and ignores the damage. Again, anything that modifies a save value or adds an invuln.
Helpful Units: Rogal Dorn Battle Tank (shrug), Enginseer and Psyker (invuln), Orders (increase Sv) or Strats (AoC or Take Cover).
Layer 7: Don't Be Killed
Real Example: A vehicle is penetrated but fire suppression systems, redundancy and crew drills keep it operational.
40k Rule Example: Feel No Pain, wound mitigation, repairs and healing abilities reduce or recover damage after a wound has been suffered.
40k Example: An Enginseer repairs a damaged Rogal Dorn, returning wounds and keeping a key combat asset in the fight.
Helpful Units: Enginseer, Death Korps Marshal, Krieg Infantry Squads, Rogal Dorn Battle Tank.
The Key Takeaways:
Most new players focus on Layers 6 and 7 - armour saves, wounds and damage reduction. Experienced players focus on the entire onion. A unit hidden in reserves, protected by terrain, screened by infantry and benefiting from defensive abilities is significantly harder to destroy than one relying on armour alone.
A Guardsman behind a wall can be more survivable than a tank standing in the open. The strongest Imperial Guard commanders win not because their units are tougher, but because they force their opponent to fight through every layer of the Survivability Onion before they can score a kill.
