Homebrew adeptus astartes Species Details

The Adeptus Astartes are among the most powerful warriors in the Imperium of Man. Created through a series of genetic enhancements and implanted organs known collectively as gene-seed, Space Marines are transformed from mortal recruits into towering transhuman soldiers. Their bodies are stronger than steel, their reflexes far beyond human limits, and their minds conditioned through relentless training and indoctrination.

Each Space Marine belongs to a Chapter, a brotherhood of warriors with its own traditions, doctrines, and battlefield specialties. Though their cultures may differ, all Chapters share a common purpose: to defend humanity and destroy the Imperium’s greatest threats. Where normal armies would falter, a handful of Space Marines can turn the tide of battle.

Clad in massive suits of power armor and wielding devastating weapons, the Astartes are more than soldiers—they are symbols. Their mere presence can rally Imperial forces or terrify their enemies. Yet despite their legendary status, Space Marines are rare, and each one is considered an irreplaceable asset in the endless wars of the galaxy.

To be an Astartes is to abandon the life of a normal human. They live only for duty, war, and the Emperor’s will, fighting without fear until death claims them or their mission is complete.

“They shall be my finest warriors, these men who give of themselves to me.”

adeptus astartes Traits

The Adeptus Astartes are not born as Space Marines—they are forged through genetic augmentation. Through a series of implanted organs known as gene-seed, a human recruit is transformed into a transhuman warrior capable of surviving the horrors of the galaxy. These implants enhance strength, reflexes, resilience, and even the ability to interface with power armor. Combined with brutal training and unwavering indoctrination, these genetic gifts make the Astartes among the deadliest warriors in the Imperium. As your character grows in experience, additional aspects of your gene-seed physiology manifest, granting new abilities that reflect the extraordinary biology of a Space Marine.

Gene-Wrought Physiology

• You gain +2 Strength or Constitution (player choice).

• You gain advantage on saving throws against disease and poison.

“We are not men. We are His Angels of Death.”

Transhuman Reflexes

When you are hit by an attack you can use your reaction to reduce the damage by:

1d10 + your Constitution modifier

Uses: Proficiency Bonus per Long Rest

Power Armor Training

While wearing Heavy Armor:

• Your movement speed is not reduced

• You gain +1 AC

Larraman’s Organ

 

When you regain HP from healing, you regain additional HP equal to your proficiency bonus.

Additionally, if you receive no healing during a round, you regain 1 HP at the start of your turn if you are above 0 HP.

Unbreakable Resolve

You gain:

• Advantage on saving throws against being frightened

• If you fail a fear saving throw, you may reroll it once.

Uses: Proficiency Bonus per Long Rest

Black Carapace

You gain:

• +1 bonus to attack rolls with weapons you are proficient with

• Advantage on checks to resist being disarmed or knocked prone

Astartes Physiology

You gain:

• Resistance to poison damage

• You can survive twice as long without food, water, or air

Angels of Death

When you reduce a creature to 0 HP, you may choose one effect:

• One ally within 30 ft gains advantage on their next attack, or

• One enemy within 30 ft must make a Wisdom save (DC = 8 + Proficiency + CHA or STR mod) or become frightened until the end of their next turn

Uses: Proficiency Bonus per Long Rest

“We are the Emperor’s fury made manifest.”