I’ve never made a secret of my admiration for the Half-Life franchise, and I wanted to try my hand at converting one of Gordon Freeman’s most famous alien adversaries (which in turn have a literary forefather in a really great Clark Ashton Smith story). The three headcrab subspecies and their respective zombies in Half-Life 2 are a favourite of mine; I love the threat palette that the trio of headcrabs create together. I have decided to unleash them upon Vaarn, so consider this an unabashed tribute to the horrid alien parasites.
They’re an interesting challenge to create Vaarn stats for, because there’s a difference between how they’re portrayed in Half Life‘s lore – horrifying parasites that can hijack your brain within minutes – and how they’re actually experienced in game, which is a fairly weak and annoying creature, only dangerous in large groups. I’ve tried to split the difference here, creating something that will try to take over a PC’s brain, but gives them a chance to prise it off as well.
If you’re making an adventure site themed around these monsters, I would strongly suggest re-playing Ravenholm to get some ideas for using the creatures for maximum impact. The Toxic Scullcrab, whose bite takes PCs to 0 HP no matter what, will become very dangerous when paired with mobs of slow and fast zombies and their respective crabs.
Obviously synths and lithling don’t have much to worry about from these creatures, so be mindful of that if your group is heavy on those ancestries.
Scullcrab
(Biological)
Level 0 (1 hp), Armour 12, Morale 2, Appearing d10
Attack: Bite (d4) / Skull Latch (d4 EGO damage, ongoing, DEX save to break free)
A reviled parasite, somewhat like a flabby shell-less crab, which seeks to latch onto the skull of a human being and chew through it, taking control of their brain. Characters reduced to 0 EGO by the Scullcrab become a Zombie, still conscious but unable to control their body, piloted around by the parasite.
Scullcrab Zombie
(Biological)
Level 2, Armour 13, Morale Never Flees, Appearing d8
Attack: Claws (d8)
What was once a human being, now puppeted by a Scullcrab, twisted by its rider into a goresoaked, dagger-clawed husk. A zombie is forced to seek out new victims for the parasites. Slow moving, relentless, and utterly without fear or mercy.
Abandon Ship: on death, the Scullcrab ejects from the zombie’s head to seek a new host. Explosives or fire prevent this.
Slow: Zombies always lose initiative.
Scullcrab, Fast
(Biological)
Level 0 (1 hp), Armour 16, Morale 2, Appearing d10
Attack: Bite (d4) / Skull Latch (d4 EGO damage, ongoing, DEX save to break free)
A lanky, fast-moving variant of the Scullcrab. Likely a weaponised evolution of its slower cousin. Characters reduced to 0 EGO by the Fast Scullcrab become a Fast Zombie, still conscious but unable to control their body, piloted around by the parasite.
Fast: Fast Scullcrabs always win initiative.
Scullcrab Zombie, Fast
(Biological)
Level 4, Armour 15, Morale Never Flees, Appearing d6
Attack: 2 x Claws (d8) / Pounce (DEX save vs Pinned, 2d6 damage ongoing)
Fast Scullcrabs impose a metamorphic horror on their hosts. The zombie’s body sheds skin and fat, becoming a lanky, elongated nightmare of muscle and exposed bone. Razorous claws complete the picture. Fast Zombies are adept climbers and swimmers, unlike their slower relatives.
Abandon Ship: on death, 1 Fast Scullcrab ejects from the Fast Zombie’s head to seek a new host. Explosives or fire prevent this.
Fast: Fast Zombies always win initiative.
Scullcrab, Toxic
(Biological)
Level 0 (1 hp), Armour 13, Morale 2, Appearing d4
Attack: Bite (CON Save vs Neurotoxin) / Skull Latch (d4 EGO damage, ongoing, DEX save to break free)
A long-legged, black-fleshed variant of the Scullcrab, sporting large poisonous fangs. Likely a weaponised evolution of its non-toxic cousin. Characters reduced to 0 EGO by the Toxic Scullcrab become a Toxic Zombie, still conscious but unable to control their body, piloted around by the parasite.
Neurotoxin: biological creatures inflicted with neurotoxin lose all remaining HP. If inflicted with neurotoxin while in negative HP, the character dies immediately.
Scullcrab Zombie, Toxic
(Biological)
Level 5, Armour 16, Morale Never Flees, Appearing 1
Attack: 2 x Claw (d8) / Toxic Scullcrab Fling (Special)
Toxic Scullcrabs inflict monstrous degradations on the human beings they puppet, their Zombie’s body bloating to twice its natural size due to the constant flow of neurotoxins into their flesh. Their swollen frames become nurseries for a new generation of Toxic Scullcrabs, which roost upon their hunched backs.
Toxic Scullcrab Fling: the Zombie pulls a Toxic Scullcrab from its back and throws it at a target. On a hit, the target is bitten and must save vs Neurotoxin (see above).
Abandon Ship: on death, d4 Toxic Scullcrabs escape from the Zombie’s corpse to seek new hosts. Explosives or fire prevent this.
Slow: Toxic Zombies always lose initiative.
VAULTS OF VAARN 