Leviathan Dreadnought Guide — Heavy Siege Walker

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What Is a Leviathan Dreadnought?

The Leviathan Dreadnought is one of the largest and most heavily armed Space Marine walkers — a siege engine built for brutal, grinding warzones where only overwhelming force will do. On the Warhammer 40,000 tabletop, it is a durable heavy-hitter with weapons that can threaten almost anything on the battlefield.

Bigger than a standard Dreadnought and even a Redemptor, the Leviathan was designed to break fortified positions and fight the enemy’s heaviest war machines. It carries a heavy weapon on each arm and can be configured for anti-armour, anti-infantry or close assault. With thick armour, a high wounds count and an invulnerable save, it is a centrepiece model that demands an answer from your opponent.

In a Space Marine army, the Leviathan fills a role close to a battle tank: a single, expensive model that walks alongside your infantry and draws a large share of the enemy’s anti-tank fire.

Leviathan Dreadnought Lore

The Leviathan-pattern siege Dreadnought dates back to the Great Crusade and the Horus Heresy, when the Mechanicum supplied it to the Legiones Astartes as a heavy siege platform. Where standard Dreadnoughts were versatile battlefield walkers, the Leviathan was built for one purpose: to break the enemy’s strongest defences and destroy their heaviest war machines.

Its armour is much thicker than a standard Dreadnought’s, its reactor more powerful and its servos stronger, so its arm mounts can carry siege weapons that a lighter chassis couldn’t handle. As with every Dreadnought, the pilot is a mortally wounded Space Marine entombed in the sarcophagus at its heart.

During the Horus Heresy, Leviathans fought on both sides, in loyalist and traitor Legions alike, and they were especially prized in siege warfare. That history is why the Leviathan is a core unit in The Horus Heresy game.

In the 41st Millennium, Leviathan Dreadnoughts are rare relics. Each surviving example is maintained with great care by Chapter Techmarines, and a Chapter does not commit one lightly, knowing its loss would be hard to replace.

Datasheet Overview

The Leviathan’s datasheet reflects a walking siege engine: high Toughness, a large pool of wounds, a 2+ armour save and an invulnerable save that keeps it standing against the heaviest weapons. Its Movement is steady rather than fast — it is a relentless pressure piece that advances while shrugging off fire.

Its close-combat arms, the siege claw and siege drill, hit with enormous Strength and Damage, capable of tearing apart vehicles and monsters. Loadouts built around ranged weapons still have useful melee from the sheer size of the walker.

Older versions of this guide talked about the CORE keyword and a Captain’s re-roll aura. Those rules belong to 8th and 9th Edition and no longer exist. In 11th Edition, characters join infantry units as Leaders or Support before the battle; they can’t simply stand next to a Dreadnought and buff it. Support for a Leviathan now comes from your detachments and stratagems (remembering that a unit can benefit from only one stratagem per phase) and from any repair abilities your Techmarines have on their current datasheets.

Note: exact characteristics, weapon profiles, abilities and points change with balance updates. Always check the current datasheet in the Warhammer 40,000 app or the relevant rules publication, and the latest Munitorum Field Manual.

Weapon Loadouts

The Leviathan carries two arm-mounted weapons, and the combination you choose defines its role. Each arm is chosen separately, so mixed loadouts are possible.

Grav-Flux Bombard

The grav-flux bombard fires concentrated graviton pulses that crush targets under their own mass. Like other grav weapons it is built to punish heavily armoured targets, which makes it a strong choice when you expect to face vehicles, monsters and heavily armoured infantry.

Storm Cannon Array

The storm cannon array is a massive rotary cannon that puts out a large volume of high-Strength shots. It is the flexible option, useful against infantry, elite infantry and light vehicles, and it can wear down heavier targets through sheer volume of fire.

Cyclonic Melta Lance

The cyclonic melta lance is a heavy, short-ranged melta weapon designed for destroying armour. It hits very hard against vehicles and monsters but needs to get close to do its best work, so it suits a Leviathan that is going to walk forward into the thick of the fighting anyway.

Siege Claw

Swapping a ranged weapon for a siege claw gives the Leviathan devastating melee, and the claw comes paired with a meltagun for short-range anti-armour shooting. This mixed loadout suits a Leviathan that advances aggressively and wants to fight in close combat.

Siege Drill

The siege drill is the other close-combat option — an enormous bore designed to punch through fortification walls and vehicle armour. It is the hardest-hitting single-target melee choice. Pair it with a ranged weapon on the other arm for a balanced loadout, or take two close-combat arms for a pure assault walker.

How to Use the Leviathan Dreadnought

The Leviathan is a slow, relentless pressure piece. Your plan should be to advance it into a threatening position and force your opponent into difficult choices about what to shoot.

Deployment

Deploy the Leviathan where it can advance towards a midfield objective while keeping line of sight to priority targets. Use terrain to block the enemy’s heaviest guns on turn one. Note that in 11th Edition, Vehicles and Monsters don’t get cover just for standing in a terrain footprint, so a Leviathan has to rely on blocking line of sight rather than on cover.

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Advance and Shoot

Move it towards midfield on turn one while shooting any worthwhile target. Don’t waste its weapons on low-value units — aim at the most expensive or dangerous enemy unit in range. By turn two it should be in or near midfield, controlling the centre through the threat of its weapons and melee.

Supporting the Leviathan

Rather than relying on character auras, plan your support at the army level. Pick detachments whose rules or stratagems reward Vehicles or Dreadnoughts, keep CP for a key defensive or offensive stratagem in the turn the Leviathan is most exposed, and screen it with infantry so enemy melee units can’t tie it up cheaply. A Space Marine army that invests in a Leviathan should build its list to make the most of it.

Midfield Control

Once in midfield, the Leviathan is an objective holder your opponent can’t ignore but struggles to remove. In 11th Edition objectives are terrain areas, so a Leviathan standing in or next to a central objective forces the enemy to commit a large amount of firepower to shift it — firepower that isn’t being aimed at the rest of your army.

Leviathan vs Other Space Marine Dreadnoughts

The Dreadnought range offers several options, and knowing where the Leviathan fits helps you choose.

Leviathan vs Redemptor

The Redemptor is cheaper, a little less durable and carries lighter weapons. It is the workhorse Dreadnought at a reasonable price. The Leviathan is the premium option: more expensive, tougher and harder-hitting. Take the Redemptor when you need points for other units; take the Leviathan when you want maximum impact from a single model.

Leviathan vs Contemptor

The Contemptor is a lighter, faster Dreadnought with a wide range of weapons and an invulnerable save. It fills a similar role at a lower price, with less durability and firepower. The Contemptor is the surgical option; the Leviathan is the sledgehammer.

Competitive Considerations

Points cost: The Leviathan is one of the most expensive single models a Space Marine army can take outside its characters and big tanks. Every point spent on it isn’t spent elsewhere, so make sure your list still has enough units to screen and take objectives.

Damage and repair: Large models can lose effectiveness as they take damage if their datasheet has a damaged profile, so check the current datasheet. Repair abilities from units such as Techmarines can help keep it fighting, if your current rules allow them to target it.

Rules status: In Warhammer 40,000, the Leviathan’s rules came from Forge World or Imperial Armour publications rather than the main Space Marine codex, and in 11th Edition its datasheet is in the Space Marines Warhammer Legends faction pack. Legends units are for casual and narrative games, so confirm with your opponent or tournament organiser before building a list around it.

Frequently Asked Questions

Is the Leviathan Dreadnought a Forge World model?

It started life as a Forge World resin model, but Games Workshop released a multipart plastic Leviathan Dreadnought for The Horus Heresy in 2022. The plastic kit is larger and more detailed than standard plastic Dreadnoughts but assembles like any other plastic kit, and it is available through the normal Games Workshop range. Check the current Warhammer 40,000 rules status separately, as described above.

Can I use a Leviathan in competitive tournaments?

Usually not. In 11th Edition the Leviathan is a Warhammer Legends datasheet, and most events allow only supported, non-Legends datasheets. Always check with your event organiser before committing to a Leviathan.

How do I paint a Leviathan Dreadnought?

The Leviathan’s large, flat armour panels are perfect for freehand Chapter symbols and battle damage. Paint it in sub-assemblies — body, arms and base separately — for easier access to details. If you have an older resin version, wash it in warm soapy water before priming to remove mould release agent; the plastic kit can be primed straight away. An airbrush helps with smooth base coats on the large panels, then detail with a brush.

What is the best Leviathan loadout for all-comers?

Two storm cannon arrays are the most versatile loadout, effective against everything from infantry to light vehicles. If you expect lots of heavy armour, grav-flux bombards or a cyclonic melta lance hit harder against big targets. A mixed loadout covers both but is the best at neither.

What are the Leviathan Dreadnought’s weaknesses?

The Leviathan is slow, expensive and a single point of failure. It moves steadily rather than quickly, so it can be outmanoeuvred and kept away from objectives, and its high points cost means losing it swings the game. Concentrated anti-tank fire before it reaches midfield is the usual way opponents deal with it.

Is the Leviathan Dreadnought from the Horus Heresy?

Yes. In the lore the Leviathan-pattern chassis dates from the Great Crusade and fought on both sides of the Horus Heresy, so it is a core unit in The Horus Heresy game. Surviving Leviathans are rare relics by the 41st Millennium, and in Warhammer 40,000 its rules have come from Forge World and, in 11th Edition, Legends publications rather than the main Space Marine codex.

Does the Leviathan Dreadnought have a heavy assault cannon?

Not by that name. Its rotary option is the storm cannon array, a huge multi-barrelled cannon that fills the same high-volume, high-strength role a heavy assault cannon does on smaller units. It can be taken on one or both arms, and two storm cannons is the most flexible all-round loadout.